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BEUIOGr-aEOPHYSICS  iibrkry 

mmERSITY  OF  CALIFORNIA 

405  HILGAPD  AVE. 

lOSMGELES,  CAIUK,  90024 


REVISED     EDITION', 


Ph 


7 


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1 


BY 
M.    F.    MAURY,    LL.D., 

AUTHOR   or   "PHYSICAL    OEOGRAPHT    OP   THE    SEA,"  LATE   SUPERINTENDENT  OP   THE   NAVAL 
OBSERVATORY,  WAsqiNGTON,  D.  C,  I^tc. 


REVISED 
BY   MYTTON   MAURY,    U.D. 


UNIVERSITY    PUBLISHING     COMPANY, 

New  Yokk. 

1887. 


MAURY'S     GEOGRAPHIES 


NEAV     SERIES. 


ELEMENTARY   GEOGRAPHY: 

A  revision  and  abridgment  of  the  "First  Lessons"  and  the  "World  We  Live  In."  Designed  for  Primary  and 
Intermediate  classes.  The  style  is  familiar  and  interesting.  The  arrangement  of  the  text  is  in  harmony 
with  the  latest  and  best  methods  of  instnietion.      New  Maps  and  numerous  illustrations. 

MANUAL   OF   GEOGRAPHY-REVISED: 

A  complete  Treatise  on  Mathematical,  Physical,  and  Political  Geography;  in  accord  with  the  most  recent 
methods  of  teaching.  The  subject  is  presented  in  a  bright  and  attractive  manner.  Abundant  explana- 
tions are  employed  to  awaken  and  sustain  the  interest  of  the  pupil  in  intelligent  study.  Beautiful  new 
Maps  and  Illustrations. 

PHYSICAL   GEOGRAPHY— REVISED: 

In  which  the  Natural  Features  of  the  Earth,  its  Oceanic  and  Atmospheric  Phenomena,  and  its  Animal  and 
Vegetable  Life,  are  fully  treated.  The  frosh,  attractive  style  of  the  work  and  the  interest  of  its  detail 
charm  the  pupil  and  the  general  reader.     Illustrated  with  numerous  beautiful  Maps  and  Engravings. 

WALL   MAPS  : 

With  new  and  original  features  ;  furnishing  invaluable  aid  in  teaching  Geography  in  classes,  and  comprising, 
I.  The  World.  II.  North  America.  111.  The  United  States.  IV.  South  America.  V.  Europe.  Vi.  Asia. 
VII.  Africa.     VIII.  Physical  and  Commercial  Chart  of  the  World. 

MAP-DRAWING: 

Prom  Maury's  Revised  Manual  of  Geography. 

In  ordering  the  Manual  or  the  Physical,  specify  whether  the  revised  or  the  old  is  wanted. 


OLD     SERIES. 


FIRST  LESSONS  IN  GEOGRAPHY. 
THE  WORLD  WE  LIVE  IN. 
MANUAL  OF  GEOGRAPHY. 
PHYSICAL  GEOGRAPHY. 

In  ordering  the  Manual  or  the  Physical,  specify  whether  the  old  or  the  revised  is  wanted. 


M.  F.  MAURY, 
In  the  Office  of  the  Librarian  of  Congress,  at  Washin^on. 


Press  of  J.  J.  Little  i  C\*. 

Copyright,  1883,  by  the  University  Publishing  Company,  New  York.  j^^„,  place.  Ne*  York. 


Library 

St    / 


PREFACE, 


This  volume,  together  witli  the  three  graded  Geographies  previously  published,  and  a  treatise  on  Astronomy,  forming 
the  Author's  contribution  to  the  University  Series  of  School  Books,  was  commenced  in  1806.  It  is  the  joint  laboi  of  tiis 
wife,  daugliters,  anil  self,  and  eonstitutod  one  of  the  chief  souices  of  their  homo  recreation  during  their  residence  in 
England.  There  tlie  best  sources  of  information  were  kindly  and  freely  opened  to  him.  Tliis,  combined  witli  the 
knowledge  and  experience  acquired  or  perfected  in  the  superintcndency,  for  fifteen  years,  of  the  Washington  Observatory, 
made  the  undertaking  congenial,  and  the  occupation  as  charming  as  labors  of  love  always  are. 

The  aim  throughout  the  series  has  been  to  strip  these  two  most  important  branches — Geography  and  Astronomy — 
of  dry  details  and  mere  technicalities,  to  popularize  these  fields  of  knowledge,  and  make  them  as  interesting  and 
instructive  to  students  as  possible. 

The  Author's  investigations  for  his  "Wind  and  Current  Charts,"  in  which  he  was  aided  by  the  vessels  and 
governments  of  the  maritime  nations,  and  the  insight  that  these  gave  him  into  the  Physical  Geography  of  the 
Sea  and  its  Meteorology,  also  afforded  him  some  rare  advantages  for  preparing  the  present  general  treatise  on 
Phy'sical  Geography'. 

Besides  these  special  and  original  sources  of  information,  he  has,  in  the  preparation  of  this  work,  had  access  to 
the  best  and  choicest  fountains  of  recent  geographical  and  scientific  knowledge,  and  has  revised  his  MS.  up  to  the  date 
of  going  to  press. 

A  science  of  recent  growth,  Physical  Geography  depends  for  its  truths  and  general  principles  upon  extensive 
and  prolonged  observations.  These  observations  have  been  made  for  too  short  a  time  and  over  too  limited  an  area, 
to  furnish  more  than  the  basis  for  a  complete  science.  The  quickened  and  enlarged  interest  that  has  been  awakened 
in  physical  researches,  the  more  perfect  instruments  and  appliances  that  are  now  used  and  that  will  be  still  further 
improved,  and  the  patronage  and  encouragement  of  enlightened  governments,  will  doubtless  lead  to  the  solution  of 
many  of  its  yet  unsolved  problems. 

It  has  been  one  of  the  great  aims  of  the  author  of  this  book  to  prepare  its  readers  and  students  to  understand  and 
take  an  intelligent  interest  in  this  noble  science,  and  especially  to  awaken  in  the  minds  of  the  young  that  spirit  of 
observation  and  patient  inquiry  which  has  already  won  from  nature  so  many  of  her  most  hidden  secrets. 

In  the  preparation  of  the  numerous  charts  which  enrich  the  volume,  the   author  has  had  the  assistance  of  one 

of  the   most  accomplished   chartographers   of   the   country ;  and   the  sldll   and  beauty  with    which   they  havs  been 

engraved  upon  copper  are   very  gratifying.     The   pictorial   illustrations,  which   so   abundantly  explain  the  text  and 

adorn  the  pages,  have  been  designed  and  engraved  by  some  of  the  first  artists  in   the  country,  or  obtained  from 

European  sources,  and    testify   to  the  liberality   of   the   publishers,  and   their  purpose   to   present  this  work  to  the 

public  in  a  most  attractive  garb. 

M.  P.  MAURY. 
Lbxington,  Virginia,  November,  1872. 


PREFACE    TO   THE    REVISED   EDITION. 

The  progress  of  science  anticipated  by  the  author  in  the  foregoing  preface,  has  rendered  desirable  the  preparation 
of  a  revised  edition  of  the  Physical  Geography.  While  engaged  in  this  labor,  the  reviser  has  sought  to  meet  the 
demands  of  our  schools  for  brief  books  by  abridging  somewhat  the  earlier  edition,  without,  however,  impairing  its 
completeness.  To  a  considerable  extent  a  re-arrangement  of  the  materials  has  been  adopted.  But  the  aim  has  been 
thioughout,  to  preserve,  so  far  as  possible,  the  charm  of  the  author's  style. 

The  typographical  arrangement  of  the  text,  the  topical  analysis  at  the  end  of  each  chapter,  and  the  test 
questions  wiU,  it  is  believed,  greatly  facilitate  the  use  of  the  book  in  the  class-room. 

In  the  prosecution  of  the  work  the  reviser  has  invoked  the  counsel  of  many  eminent  scientists  and  experienced 
educators.  To  them  all  he  begs  to  express  his  obligations  for  their  valuable  suggestions.  The  book  owes  much  to 
their  kind  assistance.  It  is  hoped  that  it  will  be  found  abreast  of  the  times,  and  well  adapted  to  lighten  the  labor 
of  the  teacher,  and  to  kindle  the  interest  of  the  pupil. 

MYTTON  MAURY. 


CONTENTS, 


PART  I.      THE  EARTH. 

PAOE 

I.  The  Earth  as  a  Planet 6 

II.  Plani'tary  Movements 8 

ni.  Magnetism  of  the  Earth  10 

IV.  Internal  Heat  of  the  Earth 13 

V.  Volcanoes 15 

VI.  Earthquakes 21 

PART  II.     THE  LAND. 

I.  Arrangement  of  Land  Masses  26 

II.  Forms  of  Land 27 

III.  ReUef  Forms  of  the  Continents 30 

IV.  Islands 38 

I^ART  III.     THE  WATER. 

I.  Properties  of  Water 43 

II.  Waters  of  the  Land 45 

III.  Drainage 50 

IV.  Continental  Drainage 51 


PAOB 

V.  TheSea 52 

VI.  The  Oceans 54 

VII.  Waves  and  Tides 55 

VIII.  Currents  of  the  Sea 61 

PART  IV.      THE  ATMOSPHERE. 

I.  Physical  Properties  of  the  Atmosphere 69 

II.  Climate  70 

III.  Winds  and  Circulation  of  the  Air 75 

IV.  Storms 81 

V.  Moisture  of  the  Air 85 

VI.  Hail,  Snow,  and  Glaciers 94 

VII.  Electrical  and  Optical  Phenomena 98 

PART  V.     LIFE. 

I.  Relations  between  Plants  and  Animals 101 

II.  Range  of  Plants  and  Animals  102 

III.  Man 116 

IV.  Geographical  Distribution  of  Labor 121 


LIST    OF    CHARTS. 


Solar  System 7 

Lines  of  Equal  Magnetic  Declination 12 

Distribution  of  Volcanoes 19 

The  World 24,  25 

North  America  30 

South  America 32 

Europe 33 

Asia 35 

Africa 37 

Australia 37 


Thermal  and  Tidal  Chart 59 

Currents  of  the  Sea  and  Drainage  of  the  Land. 02,  63 
Isothermal  Lines  and  Zones  of  Temperature . .  72,  73 

Winds 79 

Rains 90,91 

Distribution  of  Principal  Vegetable  Growths.104,  105 
Distribution  of  Beasts.  Birds,  and  Fishes,  .  ..110,  111 

Distribution  of  the  Races  of  Men 119 

Principal  Industrial  Pursuits  of  Different  Coun- 
tries  122,  123 


RECENT     FACTS 


CONCERNING  PHYSICAL  GEOGRAPHY 


A     SV  1'1'l.i:  M  E  X  T    TO     MAUIiVS     I'JIYSfCAL     (I  K  (id  h' A  ]■  II  Y 


Course  of  the  Guff  Sfreiim. — Tho  (lieorv  that  a 
portion  of  tlie  wiiters  of  the  Gulf  Stream  makes  the  circuit 
of  the  Gulf  of  Mexico  has  of  late  been  called  in  question. 
In  this  connection  the  following  letter  from  15.  A  Colonna, 
Assist.  Chief  Officer  in  the  U.  S.  Coast  and  Geodetic  Survey 
Department,  is  exceedingly  interesting  and  important  : 


U.  S.  Coast  and  (iEouETic  Survey  Office, 
Washington,  November  34;A,  I8fl' 


,( 


Dear  Sir: — Your  letter  of  17th  inst.  was  duly  received 
by  Superintendent  Thom  who  referred  it  to  this  Office. 
Press  of  work  on  my  return  from  a  short  leave  has  pre- 
vented earlier  attention.  I  now  have  the  honor  to  say  by 
direction  of  the  Superintendent  that  fhe  exact  facts  in  re- 
gard to  the  circulation  of  the  water  in  the  (riilf  of  Mexico 
cannot  he  stated ;  we  have  not  had  sufficient  observations. 
The  observations  of  deep  sea  curieuts,  and  the  usual  sound- 
ings were,  during  the  season  of  ly85-6,  confined  to  the  Gulf 
Stream,  on  a  line  from  Cape  Florida  (Fowey  Rock  Light 
House)  to  Great  Bahamas  ;  during  the  season  of  1886-7  the 
work  was  confined  to  the  vicinity  of  west  end  of  Cuba,  Key 
West,  and  Yucatan.  None  of  this  work  has  been  published, 
and  none  of  it  would  shed  any  particular  light  upon  the 
question  jiropounded  by  you  as  to  the  circulation  of  the 
waters  in  the  Gulf  of  Mexico.  Our  late  explorations  indicate 
that  the  axis  of  the  Gulf  Stream  hugs  the  west  coast  of 
Cuba  closely,  and  that  the  Gulf  Stream  currents  are  much 
influenced  by  the  moon  in  accordance  with  her  time  of 
transit  and  her  declination. 

So  far  as  the  Gulf  of  Mexico  is  concerned  I  do  not  think 
that  there  is  any  circular,  well-defined  current  about  its 
eircumferenoe.  The  warm  surface  water  probably  flows 
more  freely  toward  the  west  coast  of  Florida  than  it  does 
toward  the  coast  of  Texas  or  of  Mexico.  Although  this  view 
is  founded  somewhat  on  climatic  and  tidal  indications,  it  is 
largely  inferential.  As  1  have  said  before,  the  matter  is 
now  mider  consideration  ;  when  we  know  more  about  what 
takes  place  at  the  east  end  of  Cuba  and  thence  westward 
along  its  north  shore  to  the  Strait  of  Florida,  we  will  be 
ready  to  give  more  particular  attention  to  matters  in  the 
Gulf.  The  great  flow  of  water  through  the  Strait  of 
Florida,  northward,  must  be  supplied  from  somewhere  ;  its 
surface  temperature  indicates  its  recent  arrival  from  the 
tropics,  presumably  set  into  the  Carilabean  Sea,  and  up  into 
the  Gulf  of  Mexico,  by  the  trade-winds,  and  thence  pro- 
pelled in  accordance  with  the  laws  of  fluid  motion.  Whether 
the  whole  supply  of  water  for  the  Gulf  Stream  reaches  the 
Florida  Strait  around  the  west  end  of  Cuba,  or  not,  cannot 
now  be  asserted.  It  is  hoped  that  the  season's  work  of 
1887-8  will  shed  light  upon  this  subject. 

Yoiu-s,  respectfully, 

B.   A.   COLONXA. 


The  I'etoeiti/  of  the  Gulf  Stream. — Recent  ob- 
servations of  Lieutenant  I'illsbury.  of  the  United  States 
Navy,  show  that  the  velocity  of  the  (iulf  Stream  varies  with 
the  position  of  the  moon.  "The  greatest  velocity  is  about 
nine  hours  before  the  upper  transit  of  the  moon.  The 
strongest  surface  current  observed  was  five  and  one-fourth 
knots — the  weakest,  one  and  three-fourths — the  average 
three  and  six-tenths  knots."  These  results  are,  as  a  rule, 
higher  than  those  hitherto  given. 

It  appears  also  that  the  speed  of  the  surface  water  of  the 
Gulf  Stream  is  retarded  perceptibly  by  northerly  and  north- 
easterly winds,  and  accelerated  by  those  from  the  south- 
west. 

During  the  coming  winter  the  United  States  vessel  Blake, 
under  command  of  Lieutenant  Pillsbury,  will  continue  to 
investigate  the  Gulf  Stream  current.  She  will  anchor  six 
hundred  miles  north-east  of  Harbadoes.  during  January  and 
the  first  part  of  February,  and  will  be  in  the  track  of 
ships  from  South  Atlantic  ports  to  the  United  States. 
The  last  part  of  February  and  until  May  she  will  be 
between  the  West  India  Islands,  beginning  at  Trinidad 
and  ending  at  the  cold  Bahama  Channel.  It  is  expected  that 
Lieutenant  Pillsbury's  report  will  be  of  value,  and  that 
some  points  regarding  the  Gulf  Stream  currents  will  be  de- 
termined with  greater  exactness  than  as  yet  is  possible. 

Earlij  Polijnesian  Ndviyation. — Mr.  Formander 
lias  recently  made  some  interesting  and  instructive  discov- 
eries in  the  folk-lore  of  the  Polynesian  islands.  He  says 
that  "from  about  the  commencement  of  the  eleventh  cent- 
ury, for  two  or  thrPfe  hundred  years,  the  folk-lore  in  all  the 
[)rineiiial  groups  becomes  replete  with  the  legends  and  songs 
of  a  number  of  remarkable  men,  of  bold  expeditions,  stirring 
adventures,  and  voyages  undertaken  to  far-off  lands.'' 

For  seven  or  eight  generations,  the  navigators  of  the  lead- 
ing groups,  from  the  Sandwich  Islands  in  the  north  to  the 
Society  group  in  the  south,  and  from  the  Friendly  Islands 
in  the  west  to  the  Marquesas  in  the  east,  were  accustomed 
to  interchange  visits,  and  to  voyage  freely  to  and  fro.  with 
far  more  assurance  and  better  seamanship  than  were  dis- 
played by  the  early  Greek  and  Italian  sailors  in  the  Medi- 
terranean. Yet  the  distances  thus  traversed  sometimes 
exceeded  2.000  miles,  and  crossed  the  region  of  both  the 
north  and  the  south  trade  winds,  and  the  equatorial  calm 
belt. 

Such  facl:s  show  that,  in  accounting  for  the  movements  of 
population  in  primitive  times,  mere  distance  and  difliculties 
of  navigation  need  hardly  be  taken  into  account.  The  pos- 
sible bearing  of  this  upon  such  questions  as  the  Asiatic 
origin  of  the  North  American  Indians  will  at  once  be  seen. 

Sea-level. — Recent  observations  seem  to  indicate  that 
along  the  coast  there  is  no  such  thing  as  the  popular  sea- 


*t  097 


CopjTJ^ht,  18H7,  1>y  the  University  Publishing  Company,  New  York. 


\ 


RECENT    FACTS    CONCERNING    PHYSICAL   GEOGRAPHY. 


level."  The  surface  of  the  sea  at  any  given  point  on  a 
coast  will  be  higher  or  lower  in  pioportion  to  the  situation 
and  altitude  of  the  neighboring  land-masses. 

Lofty  mountains  attract  the  water  and  elevate  the  sea- 
level  above  the  average  height.  It  is  considered,  therefore, 
that  the  water,  being  attracted  by  the  enclosing  continents, 
the  surfaces  of  the  ocean  ureas  are  lower  in  the  centre  than 
at  tiie  sides.  The  dcpi-ession  of  the  Atlantic  centre  is  esti- 
mated by  some  to  be  ten  or  twelve  feet  ;  by  others  far  more. 

Great  Suit  L,(ike  is  said  to  Iiave  increased  about  twelve 
feet  in  depth  during  the  last  twenty  years.  Its  greatest 
depth  is  only  forty  feet.  The  la'ie  contains  no  living  thing 
excepting  infusoria  of  jjoorly  ilefined  form,  but  full  of  ac- 
tivity. The  finest-developed  was  about  tliree-fourths  of  an 
inch  in  length,  and  was  shaped  somewliat  like  a  lobster. 

A  Cliff  of  Glass. — line  of  the  wonders  of  the  Yellow- 
stone Park  is  a  cliff  of  obsidian,  which  Prof.  Joseph  P.  Id- 
dings,  of  the  U.  S.  Geological  Survey,  says  "is  as  true 
glass  as  any  artificially  manufactured."  The  cliff  is  about 
half  a  mile  long  by  from  150  to  200  feet  high,  and  presents 
a  partial  section  of  a  surface  flow  of  obsidian  which  poured 
down  an  ancient  slope  from  the  plateau  lying  east. 

Velocifi/  of  Advance  of  Ci/cloiiic  Storms.— The 
average  progressive  velocity  of  cyclonic  storms  is  given  by 
Professor  Loomis  as  follows  :  Bay  of  Bengal  and  China  Sea, 
8.4  miles  per  hour  ;  West  Indies,  18.7  ;  Europe,  1G.7  ;  mid- 
dle latitudes  of  Atlantic  Ocean,  18.0  ;  United  States.  28.4. 
Our  lake  region  seems,  therefore,  to  possess  the  unhappy 
pre-eminence  of  being  visited  by  the  fastest-moving,  as  well 
as  the  most  numerous  storms  in  the  world. 

"  Lost  Mi  vers. ''—NunKious  "lost  rivers"  occur  in 
the  southwestern  portion  of  the  United  States.  Among  the 
tributaries  of  the  Rio  Grande,  for  instance,  there  are  a  num- 
ber wliich  reach  the  main  stream  after  a  heavy  rain,  while 
at  other  times  they  are  "  lost "  in  a  brackish  marsh  or  small 
lake,  or  even  in  the  sand  of  their  own  bed.  One  such  stream 
is  mentioned  which  thus  disappeared  within  the  space  of 
twenty  rods. 

The  Krakatoa  Eruption. — One  of  the  most  de- 
structive volcanic  eruptions  ever  known  occurred  Aug.  27, 
1883,  in  the  island  of  Krakatoa  (or  Krakatau),  in  the  Straits 
of  Sunda,  illustrating  v-/hat  is  said  in  the  text  (p.  20),  on  the 
volcanic  activity  of  this  region.  The  small  islands  in  the 
vicinity  were  covered  to  a  depth  of  from  ten  to  thirty 
meters  with  volcanic  ashes  and  pumice,  which  also  fell  at 
sea  for  hundreds  of  miles  in  every  direction.  Two-thirds  of 
the  island  were  submerged,  and  the  water  now  covers  this 
a'ea  to  the  depth  of  150  to  1,000  feet. 

More  than  40,000  human  beings,  overwhelmed  by  the 
waves  or  buried  beneath  falling  cinders,  perished  on  the 
neighboring  islands  and  the  adjacent  shores  of  Java  and 
Sumatra.  Krakatoa  itself  was  uninhabited- 
Months  afterward,  vast  areas  of  the  ocean,  hundreds  of 
miles  away,  were  found  nearly  covered  with  floating  pumice. 
Scientific  investigation,  made  under  the  direction  of  the 
Dutch  government,  indicated  that  the  height  of  the  column  of 
steam  and  smoke  which  arose  from  the  crater  was  from  nine 
to  twelve  miles,  and  the  amount  of  solid  matter  thrown  out, 
over  four  and  a  quarter  cubic  miles.  The  noise  of  the  ex- 
plosions was  distinctly  heard  hundreds  of  miles  away. 

At  Talcahuano,  Chili,  the  ocean  rose,  on  Aug.  28,  two  feet 
above  high- water  mark,  indicating  ttat  the  great  wave 
caused  liy  the  earthquake  which  accompanied  the  eruption, 
had  traversed  the  entire  breadth  of  the  Pacific, 


The  Oil  Wells  of  Baku,  on  tin-  west  shore  of  the 
Caspian  Sea,  have  reached  a  yield  of  a  million  tons  per  an- 
num. The  earliest  wells  date  ba(;k  for  centuries,  but  only 
within  the  last  fifteen  years  has  the  work  of  obtaining  the 
oil  been  actively  ]irosecuted. 

A  New  Merv  Ort«ts.— General  Annenkoff,  a  Russian 
engineer,  proposes  to  form,  by  irrigation,  a  new  oasis  60 
to  70  miles  in  length  in  southern  Turkestan.  He  suggests 
diverting  a  portion  of  the;  water  of  the  Oxus  into  some  an- 
cient channels  running  in  the  direction  of  Werv.  The  .soil 
is  clayey,  and,  if  watered,  would,  it  is  believed,  prove  highly 
fertile.  The  oasis  of  Khiva,  and  another  near  Merv,  were 
formed  in  a  similar  manner. 

The  Charleston  Earth  i/uakes.— Pot  seveta,[  weeks, 
dating  from  October  31st,  1886,  a  large  area  of  the  United 
States,  embracing  nearly  all  the  Atlantic  Slope  and  a  con- 
siderable portion  of  the  Mississijipi  Valley,  has  been  visited 
by  a  series  of  earthquake  shocks. 

The  starling  point  of  these  disturbances  was  in  the  Caro- 
linas,  and  the  city  of  Charleston  and  its  neighborhood  were 
-the  scene  of  the  most  violent  and  disastrous  visitations. 
Beyond  this  area,  shocks  of  greater  or  less  intensity  were 
felt  as  far  north  as  Vermont,  and  even  in  the  Canadian 
Province  of  Ontario  ;  as  far  south  as  the  Gulf  of  Mexico  ; 
and  as  far  west  as  Michigan  and  Missouri.  The  most 
violent  shock  occurred  at  9.51  on  the  night  of  August  81st. 

Main  Features. — As  described  by  observers,  the  main 
features  of  the  disturbance  were  as  follows  : 

(1.)  A  tremor,  violent  and  destructive  near  the  origin, 
and  diminishing  in  intensity  toward  the  outer  bounds  of  the 
area  disturbed.  An  observer  at  Charleston  speaks  of  it  as 
a  "  i-ude,  rapid  quiver,"  agitating  the  lofty  strong-walled 
building  in  which  he  was,  as  though  by  the  hand  of  some 
resistless  power.  "From  first  to  last,"  he  says,  "it  was  a 
continuous  jar,  only  adding  force  every  instant,  until  at  the 
point  of  maximum  violence  it  seemed  as  though  no  human 
handiwork  could  withstand  the  shocks.  The  floors  heaved 
under  foot  ;  the  walls  and  partitions  visibly  swayed  to  and 
fro."  At  Baltimore,  a  cool-headed  observer  records  how,  on 
the  night  of  the  earthquake,  he  was  sitting  with  one  leg 
thrown  over  and  resting  upon  the  knee  of  the  other,  when 
he  noticed  his  suspended  foot  swaying  at  right  angles  to  the 
direction  of  his  body,  with  the  regularity  of  a  pendulum. 
At  the  same  time  he  heard  "a  sonorous  beating  of  some 
object"  in  an  adjoining  room,  keeping  time  with  the  oscil- 
lations of  his  foot.  Entering  this  room,  he  ascertained  that 
the  noise  arose  from  the  oscillations  of  his  wardrobe,  which 
was  backed  against  the  north  and  south  wall  of  the  room. 
The  oscillations  had  been  east  and  west,  and  had  caused  one 
of  the  doors  of  the  wardrobe  to  tap  against  the  partition 
between  the  two  compartments,  so  producing  the  sonorous 
sounds  alluded  to.  He  found  by  experiment  that  it  required 
a  movement  of  half  an  inch  at  6i  feet  from  the  floor  to  re- 
produce these  sounds  with  the  intensity  observed  during  the 
earth-movement. 

Although  it  is  generally  true,  as  above  stated,  that  the  in- 
tensity of  the  tremor  diminished  toward  the  outer  limits  of 
the  area  of  disturbance,  it  is  of  interest  to  notice  that  in 
this,  as  in  the  case  of  other  earthquakes,  there  were,  within 
the  area  of  disturbance,  many  places  where  the  shock  was  not 
felt  at  all.  It  is  conjectured  that  such  points  owe  their  im- 
munity to  geological  peculiarities. 

(2.)  The  sound  which  accompanied  the  tremor  was  a  sec- 
ond element  in  the  phenomenon.  This  came  from  below.  It 
resembled  the  rapid  rolling  of  some  heavy  body  over  a  floor. 


RECENT    FACTS    CONCERNING    PHYSICAL    GEOGRAITIY. 


or  the  booming  of  distant  cannon.  Liko  the  tremor,  it  was 
continuous,  and  became  a  "long  roar  and  grinding  like 
ten  thousand  rusty  chariots  on  a  rocky  road." 

The  ileslrtw/ire  effects  ot  the  cartli()uake  wore  nuiinly  con- 
ftned  to  Charleston  and  SuMiiucrvilh',  South  Carolina. 
Nearly  every  buiklingof  importance  in  the  former  ])laci!  was 
more  or  less  damaged — many  were  demolislied.  Of  the 
churclies,  .scarcely  any  were  left  in  a  condition  to  be  used. 
The  wreck  of  private  liouses  was  terrible.  A  recent  visitor 
writes  under  date  October  27  :  "  The  accounlu  have  not  been 
equal  to  what  I  saw.  I  think  every  building  is  more  or  less 
damagcid.     Piles  of  debris  are  in  every  street." 

The  terror  of  the  unfortunate  citizens  cannot  be  conceived. 
Most  of  them  passed  the  night  of  August  81,  and  several 
succeeding  nights,  in  tlie  streets  and  scjuares  Many  persons 
were  injui'cil,  and  several  were  killed  by  the  fall  of  the  walls. 
The  records  show  that  this  visitation  is  the  ninth  which  has 
occurred  at  Charleston  since  1754.  It  has  been  the  only 
seriously  disastrous  one. 

Effect  upon  Domestic  Animals. — Among  the  note- 
worthy incidents  of  the  Charleston  eartbijuake,  were  the 
effects  produced  upon  domestic  animals.  The  engine  horses 
escaped  and  ran  in  wild  affright,  snorting  and  neighing,  to 
the  terror  of  all  they  passed.  In  the  country  the  horses 
neighed  out  their  distress,  and  the  cows  bellowed  [)iteously. 
Animals  that  were  stabled  tried  to  l^reak  away,  and  failing 
to  do  so,  trembled  and  shivered  in  an  agony  of  fear.  Those 
that  were  at  large  fled  to  the  woods  and  sought  to  hide 
themselves  from  the  mysterious  danger  in  thickets  and 
swamps.  Half  an  hour  after  the  frightful  shock,  a  savage 
looking,  but  completely  scared  mastiff,  approached  a  re- 
porter in  the  city,  and  licked  his  shoes,  in  mute  appeal  for 
help. 

Cause  of  the  Earthquake. — Little  is  accurately 
known  as  to  the  causes  of  earthquakes.  An  ingenious  article 
appears  in  Science,  October  29,  I88().  by  M.  C.  Meigs,  in  which 
the  writer  suggests  that  the  phenomena  of  the  Charleston 
earthquake  may  be  all  accounted  for  on  the  supposition  that 
vast  strata  underlying  the  area  of  disturbance  have  been 
subjected  to  heat.  This  would  occasion  expansion  of  the 
part  heated — then  an  outward  thrust — then  compression, 
becau.se  the  expanding  portions  would  encounter  resistance 
from  outer  masses  not  affected  by  the  heat — then  relief  from 
compression  by  breakage. 

Experimental  Illustration. — He  considers  that  a  paral- 
lel to  this  series  of  occurrences  may  be  produced  by  holding 
a  piece  of  glass  (preferably  plate),  nearly  horizontal,  over 
the  flame  of  an  alcohol  lamp.  The  portion  heated  will  ex- 
pand ;  compression  will  result,  and  in  no  long  time  the  glass 
will  break  with  noise  and  more  or  less  shock.  "Here,"  says 
the  writer,  "  we  have  a  working  model  illustrating  all  the 
reported  phenomena  of  the  Charleston  earthquake." 

The  suggestion  is  certainly  deserving  of  consideration. 

Volcanic  Activity. — It  is  worthy  of  notice,  in  con- 
nection with  the  Charleston  earthquake,  that  there  has  been 
recently  unusual  volcanic  activity  in  other  parts  of  the 
world. 

In  May,  1886,  a  grand  eruption  of  ^tna  took  pla<;e. 

In  .luly  the  terrible  visitation  occurred  in  New  Zealand, 
which  ranks  as,  perhaps,  the  most  terrific  of  which  we  have 
record;  and  it  is  now  reported  that  an  eruption  occurred  on 
September  31st,  on  one  of  the  Friendly  group,  by  which 
seven  native  villages  have  been  destroyed.  And  intelli- 
gence now  reaches  us  that,  on  the  morning  of  September 
10th,   over  one  hundred   heavy  shocks   of   earthqvmko  oc- 


curred on  the  island  of  Ninafou,  one  of  the  Tonga  group, 
and  that  from  the  bottom  of  the  lake,  which  is  2.000  feet 
deep,  a  mountain  has  arisen  to  the  height  of  300  feet  above 
its  surface. 

Strange  Internal  Eruption. — Nine  miles  from 
Cimmaron,  on  the  Denver  and  Rio  Grande  Railroad,  in 
Colorado,  the  country  has  been  visited  by  an  internal  erup- 
tion, which  has  displaced  a  tract  about  two  miles  square. 
The  region  w.as  naturally  hilly,  with  a  heavy  covering  of 
trees.  Where  there  had  been  hills,  valleys  now  appear, 
while  the  valleys  have  been  upheaved  into  hills.  Trees 
stand  in  all  conceivable  positions,  some  of  them  being  re- 
versed, with  their  roots  free  from  dirt,  the  leaves  and 
branches  being  buried  in  the  debris.  The  water  has  dis- 
appeared from  a  large  lake,  the  bed  of  which  is  tilted  at  an 
angle  of  45  degrees.  The  whole  section  is  so  much  changed 
as  to  make  it  unknown  to  those  who  were  heretofore 
acquainted  with  it. 

Destruction  of  Wild  Animals. — The  wild  ani- 
mals of  North  America,  with  tlie  exception  of  a  few  species 
of  birds,  are  rapidly  diminishing  in  numbers,  owing  to  their 
destruction  by  human  enemies.  Where,  less  than  twenty 
years  ago,  millions  of  bisons  were  to  be  found  on  the  west- 
ern "  plains,"  there  are  now  but  small  bands,  remotely  scat- 
tered, of  a  few  dozen  each.  It  is  obvious,  therefore,  that  in 
no  long  time,  certain  of  our  animal  tribes  will  become  ex- 
tinct. 

Deep-Sea  Fauna. — The  expedition  of  the  Challenger 
in  the  years  1873-76,  put  us  in  possession  of  most  important 
information  regarding  the  animal  forms  which  exist  in  deep- 
sea  waters.     It  was  conclusively  established — 

(1.)  That  the  distribution  of  living  beings  has  no  depth 
limit,  but  that  animals  of  all  the  marine  invertebrate 
classes,  and,  probably,  fishes  also,  exist  over  the  whole  of  the 
floor  of  the  ocean. 

(3.)  It  appeared  that  the  enormous  pressure,  the  com- 
parative scantiness  of  light,  and  the  differences  in  the 
chemical  and  physical  conditions  of  the  water  do  not  in- 
fluence animal  life  to  any  great  extent,  for  among  the 
animals  captured  in  the  deepest  hauls  were  species  nearly 
allied  to  those  found  in  shallow  water. 

(3.)  The  interesting  fact  was  presented  that  depths 
beyond  500  fathoms  are  inhabited  throughout  the  world  by 
a  fauna  which  exhibits  the  same  general  features.  In  other 
words,  deep-sea  genera  have  usually  a  cosmopolitan  exten- 
sion, and  species  are  either  universally  distributed,  or  if,  in 
remote  localities,  they  differ,  there  is  still  a  close  resemblance 
among  them. 

(4.)  Some,  though  not  many,  types  were  found  existing 
at  abyssal  depths  which  were  pre\iously  considered  to  be 
extinct. 

(5.)  In  its  general  character,  the  deep-sea  fauna  resembles 
most  the  fauna  of  the  shallower  waters  of  high  northern 
and  southern  latitudes ;  no  doubt  because  the  conditions  of 
temperature,  on  which  mainly  the  distribution  of  animal 
life  depends,  are  nearly  similar  in  extreme  depths  and  ex- 
treme latitudes. 

The  above  and  other  conclusions,  based  upon  the  results 
of  the  Cluillenger  expedition,  have  been,  and  are  being, 
either  confirmed  or  modified  by  the  researches  carried  on 
by  the  United  States  Government. 

Methods  of  Work. — The  methods  adopted  now  are 
naturally  more  systematic,  rapid,  and  effective  than  those 
employed  twelve  years  ago  on  the  Challenger.     The  steamer 


RECENT  FACTS  CONCERNING  PHYSICAL  GEOGRAPHY. 


Albatross  has  been  specially  constructed  for  the  work  of 
dredging,  and  she  is  manned  by  a  very  expert  body  of  naval 
officers  and  scientists.  Every  summer,  at  least,  she  cruises  in 
deep  ocean  waters,  and  brings  back  the  results  to  the  head- 
quarters of  the  United  Stales  Fish  Commission,  at  Wood's 
Hole.  In  the  Challenger  expedition,  only  one  deep-sea 
dredging  could  be  made  in  a  day,  and  very  little  of  the 
bottom  was  secured  at  that.  On  the  Albatross  two  to  four 
dredgings  per  day  are  made  in  water  over  1,000  fathoms 
deep,  and  five  in  water  between  500  and  800  fathoms. 

It  has  been  conclusively  shown  by  these  later  researches 
that  the  proportion  of  animal  life  in  ocean  depths  is  far 
greater  than  was  indicated  by  the  Challenger's  results  ;  and, 
furthermore,  that  instead  of  the  abyssal  forms  being  com- 
paratively small,  many  of  them  are  even  larger  than  the 
analagous  forms  existing  in  shallower  waters.  Among  the 
echinodcrras  (spine-covered  animals,  of  which  our  common 
sea-urchin  is  a  type),  taken  in  depths  of  1,346  to  1,735 
fathoms,  two  species  arc  gigantic,  one  specimen  l)eing 
eighteen  inches  long. 

Results. — Reporting  the  results  of  the  work  done  in  1884, 
Professor  Verrill  says:  "Many  additions  to  the  fauna  of 
great  depths  were  made,  and  a  large  jiroportion  of  them 
are  undescribed  forms.  Some  of  the  fishes  were  of  great 
interest.  Huge  spiny  spider-crabs,  the  outstretched  legs  of 
which  measured  over  three  feet  from  tip  to  tip,  were  taken  in 
1,000  to  1,230  fathoms,  and  another  very  large  crab  occurred 
in  great  abundance  in  500  to  1,000  fathoms.  Numerous  spe- 
cies of  shrimp,  many  of  them  bright -colored,  and  some  of 
very  large  size,  occurred,  as  usual  in  the  deeper  dredgings." 

"A  striking  characteristic  of  the  deep-sea  Crustacea." 
saysProfessor  Verrill,  "  is  their  red  or  reddish  color.  A  few 
species  are  apparently  nearly  colorless,  but  the  great  majority 
are  some  shade  of  red  or  orange  ;  and  I  have  seen  no  evidence 
of  any  other  bright  color  A  few  species  from  between  100 
to  300  fathoms  are  conspicuously  marked  with  scarlet  or 
vermilion,  but  such  bright  markings  are  not  noticed  in  any 
species  from  below  1,000  fathoms." 

Perhaps  more  remarkable  than  the  matter  of  coloring  is 
what  we  learn  about  the  eyes  of  deep-sea  forms  of  life.  Of 
sixteen  species  taken  below  2,000  fathoms  by  the  Albatross 
every  one  had  eyes,  and  these  were  distinctly  faceted.  "  In 
at  least  three  of  these  species  (he  eyes  are  not  conspicuously 
different  in  size  from  those  of  allied  shallow-water  species." 

"  However  strong,  therefore,  may  be  the  arguments  of 
physicists  against  the  possibility  of  light  penetrating  the 
depths  from  which  these  animals  come,  the  color  and  struct- 
ure of  their  eyes,  as  compared  with  blind,  cave-dwelling 
species,  show  conclusively  that  the  darkness  beneath  2,000 
fathoms  of  sea-watei'  is  very  different  from  that  of  ordinary 
cavenis." 

Jted  Sunsets  and  SutiHses. — In  the  autumns  of 
1883  and  1884,  the  sky  at  sunset,  and  in  a  measure  also  at 
sunrise,  was  illuminated  with  a  peculiar  rosy  light,  which 
diffused  itself  far  up  toward  the  zenith.  The  phenomenon 
seems  to  have  been  observed  all  over  the  world. 

Various  causes  were  assigned  to  account  for  it.  Many 
scientific  men  considered  that  it  was  due  to  the  presence  in 
our  atmosphere  of  minute  volcanic  dust  emitted  during  the 
celebrated  eruption  of  the  volcano  of  Krakatoa,  which  oc- 
curred during  the  prevalence  of  the  red  sunsets.  This  ex- 
planation, however,  must  be  abandoned,  for  the  phenomenon 


made  its  appearance,  certainly  in  one  region  of  the  world, 
long  before  the  eruption. 

In  the  "  Proceedings  of  the  Manchester  Literary  and  Phil- 
osophical Society,  Vol.  XXIII.,  Sessions  1883-4,"  is  to  bd 
found  a  letter  dated  Taranaki,  New  Zealand,  in  which  the 
writer  says  that  "  for  many  weeks  before  that  eruption  this 
lurid  glow  was  most  strikingly  jicrceiitible  in  New  Zealand." 

In  commenting  on  this  letter,  in  his  report  for  1885,  Dr. 
Draper,  of  theN.Y.  Meteorological  Observatory,  says:  "  The 
latest  opinion  expressed  l)y  scientists  is  that  the  red  sun- 
rises and  sunsets  were  due  to  the  earth  passing  through 
meteoric  dust  in  space."  And  in  explanation  of  the  phe- 
nomenon being  observed  first  in  New  Zealand,  he  says  : 
''May  we  not  conceive  that  the  earth  in  1883  was  passing 
through  a  meteoric  cloud,  and  that  the  southern  hemisphere 
was  tlie  first  to  enter  that  cloud  ?  " 

Tetnperatiire  of  Deep-sen  Waters. — Observations 
made  on  the  Albatross,  during  1884.  indicated  that  the 
temperature  at  depths  of  2,000  to  2,G00  fathoms  was  about 
87"  Fahr.  This  temperature,  however,  was  also  found  at 
the  comparatively  shallow  depth  of  1,000  fathoms  Hence  it 
would  seem  that,  at  least  in  the  region  of  the  observations 
alluded  to.  the  minimum  temperature  is  reached  at  1,000 
fathoms.  The  surface  temperature  taken  at  the  same  dates 
was  about  72    Fahr. 

It  is  either  owing  to  the  cliange  of  temperature  experienced 
in  coming  from  great  depths  to  the  surface,  or  else  to  the 
removal  of  the  pressure  to  which  they  have  been  previously 
subjected,  that  nearly  all  the  deep-sea  animals  are  dead 
when  brought  up  in  the  trawl.  Some  have  enough  vitality 
to  make  a  few  feeble  motions,  but  "in  all  cases  they  af)- 
peared,"  says  Sir  W.  Thomson,  "to  have  received  their 
death-stroke  before  they  had  come  out  of  the  water."  An 
exception  to  this  general  rule  was  the  case  of  some  coral 
polyps  brought  from  a  depth  of  1,000  fathoms.  These  were 
alive  aud  expanded  when  placed  in  sea-water. 

Poiver  of  nil  Ocean  Jt'are.  —In  a  paper  by  the 
Rev.  Philip  Neale,  late  British  chaplain  at  Batavia,  in 
Leisure  Hour,  speaking  of  the  great  inundation  from  the 
sea  caused  by  the  Krakatoa  earthquake,  Java,  he  says: 
' '  One  of  the  most  remarkable  facts  concerning  the  inunda- 
tion remains  to  be  told.  As  we  walked  or  scrambled 
along,  we  were  much  surprised  to  find  great  masses  of  white 
coral  lying  at  the  side  of  our  path  in  every  direction.  Some 
of  these  were  of  immense  size,  and  had  been  cast  up  more 
than  two  or  three  miles  from  the  sea-shore.  It  was  evident, 
as  they  were  of  coral  formation,  that  these  immense  blocks 
of  solid  rock  had  been  torn  up  from  their  ocean  bed  in  the 
midst  of  the  Simda  Straits,  borne  inland  by  the  gigantic 
wave,  and  finally  left  on  the  land  several  miles  from  the 
shore.  Any  one  who  had  not  seen  the  sight  would  scarcely 
credit  the  story.*  The  feat  seems  almost  an  impossible  one. 
How  these  great  masses  could  have  been  carried  so  far  inta 
the  interior  is  a  mystery,  and  bears  out  what  I  have  said  in 
preNious  papers  as  to  the  height  of  this  terrible  wave.  Many 
of  these  rocks  were  from  twenty  to  thirty  tons  in  weight, 
and  some  of  the  largest  must  have  been  very  nearly  double. 
Lloyd's  agent,  who  was  with  me,  agreed  in  thinking  that 
we  could  not  be  mistaken  If  we  put  down  the  largest  block 
of  coral  rock  that  we  passed  as  weighing  not  less  than  fifty 
tons." 


*  Compare  page  21,  paragraph  4,  and  examples  on  page  22. 


PHYSICAL    GEOGRAPHY. 


Physical  Geography  invites  you  to  consider  tlie  terrestrial  machinery  which  makes  day  and 
night,  seed-time  and  harvest  ;  whieli  lifts  the  vapor  from  the  sea,  forms  clouds,  and  waters  the  earth  ; 
which  clothes  it  with  verdure  and  cheers  it  witli  warmtli,  or  covers  it  with  snow. 

Physical  Geography  treats  of  the  agents  that  cause  the  wonderful  circulation  of  the  waters  of 
tlie  sea,  that  diversify  the  surface  of  the  earth  with  nills  and  valleys,  and  embellish  the  landscape 
with  rivers  and  lakes. 

Physical  Geogi-aphy  views  the  surface  of  the  earth,  its  waters,  and  its  enveloping  atmosphere  as 
the  scene  of  the  operations  of  great  physical  forces,  which  by  their  united  action  render  possible  the 
life  of  plants  and  animals.  It  studies  the  life  of  the  globe  whether  on  its  surface  or  within  its  waters, 
taking  note  particularly  of  the  circumstances  wliich  arc  favorable  or  adverse  to  the  development  of 
organic  forms.     It  is  especially  interested  in  the  earth  as  the  abode  of  man. 

Observing  in  careful  detail  the  various  features  and  agencies  of  our  planet,  it  considers  them  as 
j)arts  of  a  magnificent  machine,  by  whose  operations,  under  the  guidance  of  the  Great  Designer,  this 
planet  is  made  a  dwelling-place  fit  for  man. 

It  has  been  judged  most  convenient  to  present  the  topics  treated  in  the  following  order  : 


I.  The  Earth. 
II.  The  Land. 


III.  The  Water. 

IV.  The  Atmosphere. 


V.  Life. 


PART     I, 


THE    EARTH. 


I.     THE    EARTH    AS    A    PLANET, 


1.  What  is  the  Barth ;'— The  first  question 
which  requires  to  be  answered  iu  discussing  the 
Pliysical  Geogrujjliy  of  tlie  earth  is,  wliat  is  tlie 
eartli  ? 

Ancient  Theory. — Many  centuries  of  Jiuman 
liistory  passed  before  any  one  was  able  to  answer 
this  question  correctly.  Men  saw  the  sun  in  the 
same  part  of  the  heavens  morning  after  morning, 
and  when  his  light  faded,  they  observed  that  the 
stars  were  apparently  just  wliere  tliey  had  been 
the  night   before.     It  was  concluded  that  the  sun 


EARTU  AKD  WOON   IN   SPACE 


and  stars  all  moved  round  the  earth  once  in  twen- 
ty-four hours. 

Thus  the  early  answer  to  our  question  was  that 
the  earth  was  the  centre  of  the  Universe. 

Careful  observation  seemed  to  confirm  this  idea. 
Astronomers  watched  the  heavens.  They  mapped 
down  the  stars,  and  recorded  from  night  to  night 
the  places  of  the  brightest  among  them.  They  ob- 
served that  some  of  them  did  not  change  their 
position  with  reference  to  their  companions,  while 
others  very  perceptibly  varied  theirs.  The  former 
were  called  fixed  stars.  Tlie  latter  received  the 
name  jjlanets,  or  wanderers,  from  a  Greek  word 


meaning  to  wander.  What  did  their  wandering 
mean  ?  It  was  found  that  after  certain  periods 
each  of  tlie  jilanets  returned  to  its  old  place  in  the 
heavens.  This  was  deemed  conclusive  proof  that 
the  planets,  together  with  the  sun  and  moon,  re- 
volved in  circles  round  the  earth.  This  explana- 
tion was  satisfactory  to  the  majority  of  mankind, 
but  not  to  thoughtful  astronomers. 

Theoey  of  Copernicus. — In  1542,  Copernicus, 
a  Prussian  astronomer,  startled  the  world  by  an- 
nouncing that  the  ancient  theory  was  a  mistake  ; 

, ._  that  the  sun,  not  the  earth, 

■  is  the  centre  of  tlie  Universe ; 
1  tJiat  the  planets,  instead  of 
circling  round  the  earth,  re- 
volve round  the  sun ;  and 
that  the  earth  itself  is  only  a 
planet. 

Thus  the  true  answer  to 
our  question,  learnt  only 
about  three  hundred  years 
ago,  is  that  the  earth  is  not 
utterly  unlike  the  heavenly 
bodies,  as  it  seems  to  us  to 
be ;  but  that  it  is  actually 
one  of  them,  and  that,  if  we 
were  placed  upon  one  of  the 
other  planets,  the  earth  would 
appear  as  a  shining  star-like 
jjoint  iu  the  sky. 

2.  Tite  Solar  System. 

— The  Sun  and  its  attendant  planets  with  their 
satellites,  together  with  the  ^jlanetoids  and  comets, 
constitute  what  is  known  as  the  Solar  System,  so 
called  from  the  Latin  sol,  the  sun. 

A  "system"  consists  of  one  central  body,  together  with 
other  smaller  ones  which  move  round  it. 

The  Sun. — The  sun  is  the  centre  of  the  Solar 
System.  From  it  all  tlie  jjlanets  derive  both 
heat  and  light. 

The  sun  is  a  vast  sphere  or  ball,  more  than  a 
million  times  as  large  as  the  earth.  If  we  could 
place  its  centre  where  the  centre  of  the  earth  is, 
then  the  sun  would  reach  so  far  into  space  that  it 


THE    EARTH   AS   A    PLANET. 


would  extend  almost  200,000  miles  beyond    the 
orbit  of  the  moon. 

The  sun  is  shown  by  the  spectroscope  to  contain 
many  of  the  same  materials  as  those  of  which  the 
earth  is  composed.  It  is  in  a  state  of  intense  heat, 
and  columns  of  incandescent  gases  project  from 
its  surface  tens  of  thousands  of  miles  into  space. 

The  heat  received  in  one  year  by  the  earth  from  the  sun, 


than  200  in  number.     They  are  so  small  as  to  bo, 
for  the  most  part,  invisible  to  tlie  naked  eye. 

Tlic  Secondary  PUmets  revolve  round  the  Pri- 
mary Planets,  as  the  Primaries  revolve  round  the 
sun.  They  are  also  called  moons  and  satellites. 
Our  moon  is  the  satellite  of  the  Earth. 

The  HiJndur  Theory,  which  is  held  })y  muiiy  astronomers, 
supposes  that  all  the  botlies  constituting  the  Solar  System 


THE    SOLAR     SYSTEM. 


would,  if  distributed  uniformly,  melt  a  layer  of  ice  100  feet 
ihick  eoveiing  the  entire  globe. 

The  Planets. — The  planets  are  classed  as  Pri- 
mai-y  and  Secondary. 

The  Primary  Planets  are  eight  in  number. 
They  are  Mercury,  Venus,  the  Earth,  Mars,  Jupi- 
ter, Saturn,  Uranus  and  Neptune.  These  names 
are  given  in  the  order  of  their  distance  from  the 
sun,  Mercury  being  the  nearest.  Between  Mars 
and  Jupiter  are  the  Planetoids,  or  Asteroids,  more 


were  originally  one  mass  of  matter  in  a  nebulous  or  cloud- 
like condition.  This  was  widely  diffused  through  a  certain 
portion  of  space,  and  had  a  rotary  motion.  From  causes  un- 
known to  us,  parts  of  it  successively  condensed  and  became 
semisolid.  Being  detached  or  thrown  off  from  the  general 
mass,  these  formed  the  various  members  of  the  Solar  Sys- 
tem, the  most  distant  from  the  centre  being  the  earliest 
formed.  The  sun  is  considered  to  be  a  portion  of  the  nebu- 
lous matter  which  is  in  an  incandescent  state,  owing  perhaps 
to  chemical  and  physical  changes  going  on  among  its  ele- 
ments. 


PLANETARY    MOVEMENTS. 


If  the  earth  be  represented  by  a  globe  one  foot  in  diameter, 
the  sun  must  be  represented  by  a  sphere  35  yards  in  diame- 
ter, and  be  2^  miles  from  the  globe,  so  as  to  sliow  in  proper 
proportion  the  real  size  of  tlie  two  bodies  and  the  distance 
between  them.  Jupiter,  the  largest  planet,  would  be  repre- 
sented by  a  globe  3i  yards  in  diameter  at  the  distance  of  11 
miles.  The  relative  sizes  of  the  disks  ot  the  sun  and  planets 
are  approximately  represented  below. 


RELATIVE   SIZE   OP  THE   SUN   AND   PLANETS. 

3.  Actual  Size  of  the  Barth. — The  equa- 
torial diameter  of  the  earth  is  7,935. G5  miles  ;  the 
polar,  7,899.17.  The  difEerence  is  about  26^  miles. 
The  region  about  each  pole,  therefore,  must  be  com- 
pres.«ed  13:^  miles.  The  circumference  of  the  earth 
at  the  equator  is  24,899  miles.  Itg  volume,  or 
solid  contents,-  is  about  260,000,000,000  cubic 
miles. 

The  specific  gravity  of  the  earth  is  about  5^, 
that  IS,  the  earth  is  fire  and  a  half  times  as  heavy 
as  a  globe  of  water  of  equal  dimensions  would  be. 

4.  Comparative  Insignificance  of  the 
Earth. — If  now  we  bear  in  mind  that  all  the 
fixed  stars  are  the  suns  of  other  si/stems  resem- 
l)ling  our  own,  and  in  many  cases  vastly  larger  * 
than  our  own,  and  reflect  that  the  heavens  above 
and  below  us  are  filled  with  untold  numbers  of 
such  systems,  we  shall  appreciate  the  comj^arative 
insignificance  of  our  earth. 

The  earth  is  only  one  of  the  smallest  members  of 
one  of  the  numberless  systems  which  fill  the  immen- 
sity of  space. 

*  The  subordinate  position  of  tlie  Solar  System  in  tlie  universe  is 
strongly  suggested  by  tbe  fact,  that  the  entire  system  appears  to  be  mov- 
ing through  space  in  the  direction  of  the  constellation  Hercules.  Mo- 
tion towards  indicates  an  attracting  force  ;  and  implies  that  the  body 
exerting  that  force  is  larger  than  the  body  which  is  attracted.  How 
vastly  grander  than  our  system  must  that  one  be  which  candraw  toward 
Itself  our  sun  with  itii  inconceivable  volume,  and  the  attendant  planets  I 


TOPICAL  ANALYSIS. 
I.    THK   EARTH    AS   A    PLANET. 

1.  What  is  the  Earth  1 

Ancient  Theory.    Fixed  .Stars.     Planett,.     Theory 
of  Copernicus. 

2.  The  Solar  System. 
Classesof  bodies  Included  In  it.   The  Sun.  Ilelation 

to  Solar  System.  Size.  Materials  composing  it. 
Its  heat.  Planets.  Primary  Planets.  Planetoids. 
Secondary  Planets.  Nebular  Theory.  Relative 
sizes  of  Sun  and  Planets. 

3.  Actual  size  of  the  Earth. 
Diameter.       Circumference.       \'oluine.       Sjiccific 

gravity. 

4.  Comparative  insignificance  of  the  Earth. 

Test  Questions.  — [The  test  questions  are  to  be  used  at  the 
option  of  the  teacher.  They  arc  not  directly  answered  in  the  text. 
Their  design  is  to  awaken  thought  on  the  part  of  llie  pupil.]  Name 
:dl  the  bodies  yon  can  that  may  be  seen  in  the  heavens.  What 
w  ould  be  the  consequence  to  the  earth,  if  the  lieat  of  the  sun 
should  be  withdrawn  » 


II.     PLANETARY  JIOVEMENTS. 

].  Effects  of  the  Earth's  3Iotions. 

— The  nature  of  man  requires  for  its  highest 
development  that  he  shall  have  certain  alternations 
in  the  degrees  of  light  and  heat  to  which  he  is 
subjected.  The  planetary  motions  of  the  Earth 
produce  just  the  changes  which  he  needs.  They 
are  those  of  day  and  night,  and  summer  and  win- 
ter.    Let  us  see  how  these  are  brought  about. 

2.  notation. — All  of  the  planets  rotate  on 
their  axes  from  west  to  east.*  This  motion  causes 
alternations  of  sunshine  and  darkness. 

The  nearer  a  planet  is  to  the  sun,  the  less  rapidly 
it  rotates.  Mercury,  Venus,  and  the  Earth  rotate 
in  about  twenty-four  hours.  The  more  distant 
planets,  so  far  as  their  rates  have  been  ascertained, 
require  only  about  nine  or  ten  hours  for  their  rota- 
tion.    Their  day  is  less  than  half  of  ours. 

It  is  easy  to  see  that  its  brevity  would  be  very 
inconvenient  to  beings  like  ourselves. 


ting. 


net^olntion. — The    planets,    while    rota- 

also  revolve  round  the  sun. 
The  direction  of  this  planetary  revolution  is,  like 
that  of  rotation,  from  west  to  east,  and,  with  the 
exception  of  the  satellites  of  Uranus,  and  possibly 
those  of  Neptune,  all  the  secondary  planets  revolve . 


*  An  interesting  evidence  of  the  earth's  rotation  is  that  suggested  by 
Newton.  It  is  easy  to  see  that  a  body  at  the  top  of  a  tower  will,  if  the 
earth  really  rotates,  move  with  greater  velocity  than  will  the  base  of  the 
tower.  Let  a  ball  be  dropped  from  the  top  of  such  a  tower,  and  it  will 
strike  a  point  on  the  ground  some  distance  from  the  foundation.  Ei- 
periuienfs  of  this  kind  have  all  clearly  demonstrated  the  easterly  motion 
of  the  earth,  the  balls  dropped  always  striking  to  the  eastward. 


PLANETARY    MOVEMENTS. 


ill  the  same  direct-ion.     Tlie  time  required  for  a 
single  revoJution  is  called  a  year. 

The  nearer  a  planet  is  to  the  sun,  the  more 
rapidly  it  revolves,  and  tlie  shorter  is  its  year. 
The  year  of  Mercury,  tlie  nearest  planet,  is  only 
eighty-eight  days  long  :  J  upiter's  year  consists  of 
about  eleven  of  ours  :  Neptune's  of  more  than  160. 
The  earth  completes  its  revolution  in  365^  days. 

4.  Inclination  of  Planet avy  Axes.— 

The  axes  of  the  planets  are  inclined  to  the  planes 
of  their  orbits.  The  angle  or  amount  of  inclina- 
tion is  not  the  same  for  all  the  planets.  Each  has 
its  own.  But  it  is  important  to  observe  that  the 
angle  of  inclination  of  each  jilanet  undergoes  no 
change.  It  is  said  to  be  "constant."  And  again 
the  axis  of  each  jilanet  preserves  invarialily  the 
same  direction  at  every  point  of  the 
orbit  ;  in  other  words,  at  any  two 
jioints  of  the  orbit  the  axis  is  ]iar- 
allel  to  itself. 

The  facts  that  the  planetary  axes 
are  inclined  at  constant  angles,  and 
preserve  unchanging  directions, 
bring  about,  in  combination  witli 
the  revolution  of  the  planets,  two 
results  :  (1)  changes  of  seasons  ; 
(2)  variations  in  the  duration  of 
day  and  night. 

SEASON'S. — An  inspection  of  the 
cut  opposite  will  show  that  as  eacli 
planet  passes  round  the  sun,  the 
upper  portion  of  its  surface  will 
be  directed  toward  tlie  sun  at  one 
part  of  its  orbit,  the  lower  at  the 
opposite  part.  In  other  words,  the 
northern  hemisiihere  of  each  planet 
will  receive  the  more  direct  rays  of 
the  sun  at  one  time,  the  southern 
at  another.  A  hot  season,  or  sum- 
mer, will  therefore  alternate  with  a  cold  season  or  i 
winter. 

Tlie  EartVs  Axis  is  inclined  to  the  plane  of  its 
orbit  at  the  constant  angle  of  about  23^°.  This 
inclination,  combined  with  the  earth's  orbital  mo- 
tion, makes  o?</'  seasons. 

The  sun  appears  eveiy  year  to  move  through  the  heavens 
northward  as  far  as  the  Tropic  of  Cancer,  and  southward  as 
far  as  the  Tropic  of  Capricorn.  In  the  course  of  this  jour- 
ney he  is  directly  over  our  equator,  or,  to  use  the  sailor's 
phrase,  "crosses  the  line,"  on  or  about  the  21st  of  March. 
Just  as  soon  as  he  passes  northward  of  the  equator,  his  light 
leaves  the  south  pole,  and  extends  to  and  beyond  the  north. 
The  winter  of  the  south  polar  regions  now  begins,  and  tliat 
of  the  north  polar  regions  ends.  Still  travelling  north- 
v/ard  Ihe  sun  carries  the  hot  season  with  him,  and  summer 
prevails  throughout  the  northern  hemisphere. 

The  reverse  of  all  this  occurs  while  the  sun  Journeys 
southward. 


'Varying  Length  of  Day  and  Night. — A 
second  effect  of  this  inclination  of  the  axes  of  the 
planets  to  their  orbits  is  tliat  their  periods  of  light 
and  darkness,  or  day  and  night,  vary  in  length 
according  to  the  ajiparent  position  of  the  sun  at 
the  different  seasons. 

In  the  case  of  the  earth,  twice  every  year,  in  March  and 
in  September,  when  the  sun  crosses  the  equator,  the  equinox 
occurs;  that  is,  daylight  and  darkness  are  of  equal  dura- 
tion all  over  the  globe.  Each  is  twelve  hours  long.  This 
is  because  the  light  of  the  sun,  when  he  is  on  the  equator, 
extends  from  pole  to  pole,  and  one  half  of  every  parallel  is  in 
sunlight  and  the  other  half  in  shade.  But,  as  the  sun  moves 
northward,  the  duration  of  daylight  is  greater  and  greater 
for  all  places  north  of  the  equator,  until  about  the  21st  of 
June,  when  the  summer  solstice  occurs.  Then  the  north 
pole  of  the  earth  is  turned  toward  the  sun  and  the  northern 
hemisphere  has  its  longest  day. 


ORBIT    nP    THt    EAUTH. 


The  sumra'er  solstice  being  past,  the  sun  begins  to  recede 
toward  the  south.  Our  days  then  become  shorter  and 
shorter,  until,  toward  the  end  of  December,  we  have  our 
shortest  day.  The  sunshine  then  lasts  for  us  only  about  nine 
hours.  The  winter  solstice  being  past,  the  days  again  be- 
gin to  lengthen .  [For  the  effect  of  this  upon  the  climate 
of  northern  latitudes  see  paragraph  2  on  page  70.] 

5.  Adaptation  of  the  Earth  for  Hu- 
man Habitation. — Comparing  the  earth  with 
the  other  planets,  we  observe  two  points  which 
render  it  specially  adapted  for  human  habitation : 
(1)  its  position  with  reference  to  the  sun  ;  (2) 
the  moderate  inclination  of  its  axis. 

Owing  to  its  distance  from  the  sun,  and  the 
consequent  moderate  intensity  of  its  heat  and  cold, 
as  well  as  the  medium  length  of  its  year,  the  earth 
occupies  a  most  favored  situation  in  the  Solar  Sys- 
tem.     We  are  not   so   near  to  the  sun  as  to  be. 


MAGNETISM    OF   THE    EARTH. 


like  Mercury,  exposed  to  destructive  heat ;  nor  are 
we  so  remote  as  to  encounter  unendurable  cold. 
The  nearer  planets  must  be  too  hot ;  the  more  dis- 
tant quite  too  cold  for  human  habitation. 

Again  ;  the  length  of  our  year  and  the  dura- 
tion of  its  seasons  are  admirably  suited  to  human 
needs.  Supposing  Mercury,  Jupiter  and  Neptune 
to  have  four  seasons  as  we  have,  it  is  obvious  that 
tiiey  would  be  entirely  unsuited  to  be  the  resi- 
dence of  beings  like  ourselves.  The  seasons  of 
Mercury  would  be  about  three  of  our  weeks  in 
length  ;  those  of  Jupitei',  three  of  our  years  ;  while 
on  the  planet  Neptune  a  single  season  would  be 
forty  earthly  years  in  duration. 

Owing,  moreover,  to  the  moderate  inclination  of  its  axis, 
the  earth  has  polar  regions  of  restricted  extent.  The  vast 
proportion  of  its  surface  is  habitable  for  man. 

It  is  obvious  [  see  cut,  p.  9  ]  that  what  we  call  the  polar 
regions  of  each  planet  are  of  greater  or  less  extent  in  pro- 
portion to  the  amount  of  inclination  of  the  planetary  axis. 

The  inclination  of  the  axis  of  Venus  is  believed  to  be  75°. 
Consequently  its  polar  regions  will  extend  75°  from  either 
pole.  Nearly  the  whole  surface  of  the  planet,  therefore, 
must  have  only  two  seasons  ;  one  of  intense  heat,  the  other 
of  equally  intense  cold. 

TOPICAL  ANALYSIS, 
n.    PLANETARY   MOVEMENTS. 

1.  Effects  of  the  Earth's  Motions. 

Influence  npon  lliL' needs  of  man. 

2.  Rotation  of  Planets. 

Direction.  Relation  of  velocity  of  rotation  to  dis- 
tance from  sun. 

3.  Revolution. 

Direction  of  tlie  motion.  Relation  of  velocity  of 
revolution  to  distance  from  svin.     Illustrations. 

4.  Inclination  of  Planetary  Axes. 

Unchanging  amount  and  direction  of  the  inclina- 
tion. Results  ill  clian<;e  of  seas(ms.  In  varying 
length  of  day  and  nijjiit.  Equinoxes  and  sol- 
eticcs. 

5.  Adaptation  of  the  Earth  for  human  habitation. 

Two  c:uises  of  this  adaptation.  Seasons  of  the 
other  planets. 

Test  Qxtestions.— If  (he  inclination  of  the  earth's  axis  were  increased, 
how  would  that  affect  our  seasons?  IIow.  if  the  inclination  were  dimin- 
ished ?  Where  are  the  snn's  rays  verticiil  when  we  have  our  longest 
day?    Where  are  they  vertical  when  tlie  days  and  nights  are  equal  ? 

III.     MAGNETISM  OP  THE  E.A.RTH. 

1.  How  denionsf rated. — Among  the  prop- 
erties which  belong  to  the  earth  as  a  whole,  is 
its  Magnetism.  An  understanding  of  this  subject 
is  best  reached  by  noticing  the  phenomena  of  those 
bodies  which  we  call  Magnets,  and  then  comparing 
with  these  phenomena,  certain  ones  which  arc  ex- 


hibited by  the  earth.  The  result  will  demonstrate 
that  the  earth  is  a  magnet. 

2.  M<t<jttets. — Magnets  are  either  natural  or 
artificial.  The  ])r(i]ierties  exhibited  by  ))oth  are 
identical. 

Natural  Magnets  are  pieces  of  a  kind  of 
iron  ore  commonly  called  the  loadstone.  This 
ore  was  first  found  near  a  city  of  Asia  Minor  called 
Magnesia ;  and  hence  the  magnet  received  its  name. 

Artificial  Magnets  are  readily  made  by  rub- 
bing a  piece  of  tempered  steel  upon  a  natural 
magnet,  or  upon  a  bar  of  steel  already  magnetized, 
or  by  the  employment  of  currents  of  electricity. 
According  to  their  shape  and  size  artificial  magnets 
are  called  lar  magnets,  horseshoe  magnets,  or  mag- 
netic needles.  The  last  are  such  as  are  employed 
in  compasses. 

3.  The  Projterti'es  of  the  Mciffnet  are 

among  the  most  extraordinary  of  material  phenom- 
ena.   They  are  closely  akin  to  those  of  electricity. 

Magnets  attract  pieces  of  iron  and  steel.  They 
also  attract  other  magnets.  This  action  will  occur, 
even  though  the  magnet  and  the  body  attracted 
are  at  a  considerable  distance  from  each  other,  or 
even  if  some  substance,  like  glass,  intervene  be- 
tween the  two. 

Magnets  have  poles. — If  a  magnet  be  sus- 
pended so  as  to  be  free  to  move,  one  end  of  it  points 
invariably  to  the  north,  the  other  to  the  south. 
The  two  ends  are,  therefore,  called  the  north  pole 
and  south  ])ole  of  the  magnet. 

If  now  we  bring  two  magnets  near  one  another, 
a  very  singular  effect  is  produced.  The  north  pole 
of  the  one  is  attracted  toward  the  south  jjole  of  the 
other;  the  south  pole  of  the  one  is  drawn  toward 
the  north  pole  of  the  other.  But  if  the  north  pole 
of  the  one  be  presented  to  the  north  pole  of  the 
other,  they  rejjcl  one  another.  The  north  pole  of 
the  one  that  is  free  to  move  swings  away.  In  like 
manner,  if  the  two  south  poles  be  placed  near  one 
another,  they  mutually  repel. 

Thus  we  see  :  (1)  that  the  magnetic  forces  at  the 
opposite  poles  are  ojjposite  in  certain  respects;  and 
(2)  that  like  poles  repel,  utilike  attract. 

Neutral  Line. — About  half- way  between  the 
uoi'th  and  south  poles  there  is  a  neutral  line,  ex- 
tending across  the  magnet.  Along  this  line  the 
opposite  magnetic  forces  neutralize  each  other. 

If  a  piece  of  iron,  or  a  magnetic  needle,  be  suspended  ex- 
actly over  this  line,  it  will  not  be  attracted  at  aU.  On  either 
side  of  it,  however,  a  suspended  needle  is  drawn  toward  one 
or  the  otlier  of  the  poles.  The  ixaet  position  of  the  neutral 
line  depends  on  the  relative  strength  of  the  poles.  As  these 
are  seldom  if  ever  of  equal  strength,  the  neutral  line  will 
rarely  or  never  be  equidistant  from  both. 


MAGNETISM    OF   THE    EARTH. 


II 


4.  The  FAirth  a  Mdffurt. — In  some  very 
important  respects  the  eartli  behaves  like  ii  magnet. 

Attractive  Power. — lu  the  first  place  it  dis- 
plays attractive  power  precisely  similar  to  that  of 
the  maffuet.  It  is  terrestrial  magnetism  which 
causes  magnets  to  point  nortli  ward  when  suspended. 

Magnetic  Poles. — Secondly,  like  the  magnet 
the  earth  has  magnetic  poles.  These  are  not  ex- 
actly at  the  north  and  swith  geographical  poles, 
but  at  some  distance  from  them.  They  are  the 
points  at  which  the  needle  stands  vertical.  The 
north  magnetic  pole  is  in  North  America.  It  is 
situated  in  Boothia,  latitude  70°-north,  longitude 
97°  west.  The  discovery  of  this  pole  was  made 
by  Sir  James  Eosa  in  1830. 

The  position  of  tbe  soutli  magnetic  pole  has  not  been  so 
accurately  determined.  Sir  James  Ross  reached  a  point  in 
the  Antarctic  Ocean  where  the  inclination  was  88  37',  from 
which  its  situation  has  been  computed.  It  is  not,  however, 
diametrically  opposite  the  north  magnetic  pole,  but  far  to 
one  side.  It  lies  in  the  vicinity  of  lat.  75"  S.,  long.  134  E. 
The  position  of  both  these  poles  is  constantly  changing. 

Neutral  Line. — Thirdly,  the  earth,  like  a  mag- 
net, has  a  neutral  line.  This  line  encircles  the 
globe  about  midway  between  the  north  and  south 
magnetic  poles.  Along  it  the  opposite  polar  forces 
counteract  each  other.  It  is  called  the  magnetic 
equator.     Its  course  is  traced  upon  the  chart. 

5.  Inclinattoii  or  Dij)  of  the  Needle. — 

As  you  go  northward  from  the  magnetic  equator, 
the  north  end  of  the  needle  is  drawn  downward 
from  a  horizontal  position  until  you  reach  the  mag- 
netic pole,  and  there  the  needle,  as  already  said, 
points  vertically.  As  you  go  southward  from  the 
magnetic  equator,  the  south  pole,  in  like  manner, 
is  drawn  down,  until  at  the  south  magnetic  pole 
the  needle  would  again  become  vertical. 

The  amount  of  deviation  from  the  horizontal 
position  is  called  the  Inclination  or  Dii)  of  the 
needle.  Only  upon  the  magnetic  equator  or  neu- 
tral line  is  there  no  dip. 

6*.  Declination  of  tJte  Needle. — While 
magnets  free  to  move  assume  a  north  and  south 
direction,  they  do  not  point  exactly  to  the  true 
geographical  north,  bat  a  little  to  the  west  or  the 
east  of  it.  The  deviation  from  the  true  northerly 
position  is  called  the  declination  of  the  needle. 

Declination  differs  in  different  places,  both  in 
direction  and  amount. 

The  direction  in  some  places  is  east,  in  others  west.  It 
will  be  seen  from  the  map  that  over  about  one  half  of  the 
globe  it  is  easterly,  over  the  other  half,  westerly.  The 
amount  of  declination  is  greater  in  some  places  than  others. 
In  Liverpool,  Edinburgh  and  Glasgow,  it  is  about  two  de- 
grees greater  than  at  Loudou. 


Variations. — The  intensity  and  position  of  the 
forces  which  cause  the  needle  to  deviate  from  the 
true  north  and  south  direction  are  constantly 
changing.  Hence  there  arise,  (1)  secular  varia- 
tions ;  (2)  diuriuil  variations. 

Secular  Variations  extend  over  hmg  |ierinds.  The  decli- 
nation at  London  wascust  in  1580,  and  aiiiountid  to  11"  30'; 
in  1003  it  was  zero  ;  in  1818  it  attained  its  maximum,  24" 
41',  and  was  west.  In  1877  it  had  decreased  to  19'  3'  west. 
It  is  therefore  decreasing  at  the  rate  of  about  5'  annually; 
so  that  in  200  years  it  will  probably  be  east  again. 

In  diurnal  variations  the  needle  moves  from  east  to  west, 
from  8  A.M.  till  noon,  and  back  again  in  tlie  afternoon.  In 
Washington  City  the  variation  is  about  14'. 

Line  of  no  Variation.* — Just  as  there  is  a 
magnetic  equator  along  which  there  is  no  dip  or 
horizontal  deviation,  so  there  are  lines  on  which 
there  is  no  declination.  Such  lines  are  commonly 
known  as  "  lines  of  no  variatioji."  \ 

There  are  two  such  lines,  one  in  the  eastern 
hemisphere,  and  one  in  the  western.  Their  posi- 
tion is  constantly  changing.  In  the  time  of  Co- 
lumbus the  western  line  was  about  20°  west  of  the 
Azores.     It  now  passes  through  the  West  Indies. 

7.  Maffuetic  Storms. — Unusual  and  violent 
fluctuations  of  the  needle  indicate  the  prevalence 
of  magnetic  storms.  Such  storms  take  place  dur- 
ing displays  of  lightning,  but  more  particularly 
durino;  the  occurrence  of  the  Aurora  Borealis.  One 
of  the  most  violent  on  record  occurred  November 
17th,  1882.  It  prevailed  throughout  the  United 
States,  and  even  extended  to  Europe.  Chicago 
seems  to  have  been  the  focus  of  the  disturbance. 
Here  "  ojierating  keys  "  were  in  some  cases  melted. 
Telegraphic  communication  was  practically  sus- 
pended throughout  the  country,  and  even  the 
ocean  telegraphs  were  disabled  for  many  hours. 

8.  Su)i-S2)Ots  and  Terrestrial  Maf/- 
netisni. — It  is  believed  that  there  is  a  relation 
between  the  spots  observed  upon  the  sun  and  the 
magnetism  of  the  earth. 

The  sun-spots  are  periodical,  both  as  to  number  and  fre- 
quency. They  attain  their  maxima  and  minima  in  from 
ten  to  twelve  years.  The  magnetism  of  the  earth  seems  to 
follow  the  same  law  of  variation.  Auroras  and  magnetic 
disturbances  appear  to  be  most  frequent  when  the  sun- 
spots  are  most  numerous.  Hence  it  is  argued  that  some  in- 
timate relation  probably  exists  between  these  phenomena. 


*  The  interest  attaching  to  this  line  is  great.  Spain  and  Portugal 
quarreled  about  tlie  possession  of  the  lands  discovered  oy  iheir  navi- 
gators in  the  16th  century.  The  pope  directed  that  the  "  line  of  no  varia- 
Hon  "  should  be  the  boundary  between  tliem.  All  lands  discovered  to  the 
eastward  of  this  line  were  to  belong  to  Portugal,  :ill  to  the  westward  to 
Spain.  Spain  was  determined  to  possess  herself  of  some  of  the  East 
India  Sp'ce  islands,  but  she  could  claim  them  only  by  making  it  appear 
that  they  were  to  the  westward  of  the  20th  meridian.  Hence  Magellan 
proposed,  in  the  interest  of  the  King  of  Spain,  to  reach  the  Moluccas  by 
sailing  westward.  His  voyage  resulted  in  the  circumnavigation  of  the 
globe.  t  Variation  here  means  declination. 


INTERNAL  HEAT  OF  THE  EARTH. 


'3 


Note  upon  the  map. — The  buff  color  indicates  easterly  dec- 
lination, the  blue  westerly.  The  lines  which  diverge  from 
the  magnetic  poles  have  numbers  afli.\ed  to  theju  which  show 
the  amount  of  declination.  A  curious  oval  is  observed  upon 
the  buff  space.  It  embraces  part  of  China  and  the  .Japanese 
Islands.  Within  its  limits  the  declination  is  abnormal.  It 
is  westerly.  From  this  it  is  inferred  that  there  probably 
exists  another,  though  subordinate,  n<.'rth  magnetic  pole  in 
Northern  Asia. 


,9.  Causes  of  Terrestrial  Magnetism. 

— If  a  current  of  electricity  is  made  to  pass  round  a 
piece  of  soft  iron,  the  latter  acquires  magnetic  prop- 
erties, and  retains  them  so  long  as  the  current 
lasts.  If  vast  currents  of  electricity  passed  round 
and  round  the  earth,  they  would  convert  it  into  a 
gigantic  magnet.  This,  it  is  believed,  actually 
occurs. 

The  sun's  rays,  resting  successively  on  different 
l^ortions  yf  the  earth's  surface  as  it  rotates,  pro- 
duce thermo-electric  currents  ;  i.e.  electric  currents 
produced  by  heat.  These  follow  the  apparent 
course  of  the  sunlight  from  east  to  west  round  the 
globe,  and  convert  the  earth  into  a  magnet. 

The  above-noted  relation  between  magnetism 
and  sun-spots  seems  to  corroborate  this  theory. 

10.   Uses  of  Terrestrial  Ma{/netistn. — 

It  might  seem  that  the  magnetism  of  the  earth  is 
only  a  carious  and  interesting  fact.  But  its  bear- 
ing upon  the  welfare  of  the  human  family  is  mar- 
vellous. To  it  we  owe  the  compass,  and  to  the 
compass  tlie  possibility  of  modern  navigation. 
Without  his  magnetic  needle  ever  pointing  north- 
ward, how  could  the  mariner  find  a  pathway 
over  the  trackless  waters,  and  steer  unerringly  for 
"  the  haven  where  he  would  be  ?  " 


TOPICAL  ANALYSIS. 
III.    MAONETISM   OF   THE   EARTH. 

1.  How  demonstrated. 

2.  Magnets. 

N;iliir!il.     Origin  of  name.      Artificial.      Modes  of 
making.    Kinds. 

3.  Properties  of  the  Magnet. 

Attraclion.    Slagnctic  Poles.    Law  of  magnetic  at- 
traction.   Neutral  line. 

4.  The  Earth  a  Magnet. 

Attractivi-  power.    Magnetic  Poles.     Neutral  line. 

6.    Inclination  or  Dip  of  the  Needle. 

Effect  upon  the  needle  of  approaching  the  magnetic 
pole. 

6.    Declination  of  the  Needle. 

Definition.      Variations   in    declination.     Secular. 
Diurnal.    Line  of  no  variation. 


7.    Magnetic  Storms. 

IndicjitionK.     TimcH  of  occurrence. 

8     San-spots  and  Terrestrial  Magnetism. 

SiippoHcd  relation  between. 

9.    Cause  of  Terrestrial  Magnetism. 

Influence  of  eliTtrie  i-iirrents. 

10.    Uses  of  Terrestrial  Magnetism. 

Note.— In  connection  with  tliis  subject  the  teaclier  might  advert  to 
the  disturbing  effects  of  iron  vessels  upon  compasses  ;  the  less  of 
vessels  from  this  cause,  and  tlie  means  adopted  to  counteract  the  attrac- 
tion of  the  iron  used  in  the  construction  of  vessels. 


IV.  INTERNAL  HEAT  OP  THE  EARTH. 

1.  Evidences  of  Internal  Heat. — While 

the  crust  of  the  earth  is  generally  of  a  moderate 
temperature,  there  are  various  reasons  for  believing 
that  its  interior  is  in  a  state  of  intense  heat.  Three 
sources  of  proof  may  be  mentioned  :  (1)  mines  ; 
(2)  hot  springs,  geysers,  and  artesian  wells ;  (3) 
volcanoes. 

Mines. — As  we  descend  througli  mines  into  the 
interior  of  the  earth,  Ave  find  the  temperature  to 
increase  at  the  rate  of  about  1°  Fahrenheit 
for  every  50  feet  of  perpendicular  descent.  In  very 
deep  mines  it  is  impossible  for  miners  to  exist  with- 
out a  constant  current  of  fresh  air  to  reduce  the 
temperature.  A  limit  is  soon  reached,  beyond 
which,  owing  to  the  increa.se  of  heat,  mining  is 
impracticable. 

The  greatest  depths  at  which  miners  have  found 
it  possible  to  work  are  about  2,500  feet  below  the 
surface. 

In  the  Consolidated  Virginia  and  California  Mine  in  Vir- 
ginia City,  which  has  a  depth  of  2,000  feet,  the  temperature 
is  115°  Fahrenheit.  The  miners  are  divided  into  gangs, 
each  gang  working  twenty  minutes  and  resting  forty.  They 
drink  ice  water  freely,  and  apply  ice  to  their  wrists  to  cool 
the  circulation. 

At  Monderf,  in  Luxenibiirg,  a  mine  has  been  sunk  to  the 
depth  of  3,920  feet,  and  one  at  New  Salzwerk,  in  Prussia, 
is  2,380  feet  deep. 

Artesian  Wells  bear  testimony  to  the  same 
rapid  increase  of  heat.  These  have  been  sunk  in 
various  parts  of  Europe  and  America  to  a  depth 
varying  from  1,000  to  4,000  feet. 

In  Europe  the  average  increase  of  temperature 
is  1°  Fahrenheit  for  about  55  feet ;  in  America, 
1°  for  about  70  feet.  The  temperature  of  the  well 
at  Grenelle,  near  Paris,  is  81.7°  Fahrenheit.  Its 
depth  is  1,798  feet.  That  at  Buda-Pesth  is  3,160 
feet  deep.  Its  temperature  is  178°  Fahrenheit. 
It  supplies  a  large  part  of  the  city  with  warm 
water. 

Experience  shows  that  by  boring  artesian  wells, 
jets  of  warm  water  may  be  obtained  in  almost  every 
region  of  the  earth. 


14 


INTERNAL  HEAT  OF  THE  EARTH. 


Hot  Springs  are  found  in  countless  numbers  in 
various  parts  of  the  world.  They  are  most  abun- 
dant in  volcanic  regions;  but  they  are  not  con- 
fined to  tlie  vicinity  of  volcanoes.  Those  of  Bath, 
in  England,  are  more  than  1,000  miles  from  either 
Etna  or  Vesuvius.  More  than  1,500  exist  in 
Euroi)e.  The  cut  below  shows  those  of  St.  Michael, 
one  of  the  Azores. 


BOILING   SPRINGS  OP  ST.  MICHAEL   (AZORES). 

The  temperature  of  these  springs  seems  to  indi- 
cate that  cverjTvhcre,  not  far  below  the  surface  of 
the  ground,  some  source  of  high  heat  exists.  The 
Arkansas  hot  springs  vary  from  110°  to  150°  Fah- 
renheit. One  of  those  in  Iceland  is  49°  aljove  the 
boiling  point. 

Geysers  are  intermittent  hot  sjjrings.  The 
temperature  of  their  waters  rapidly  rises  with 
every  few  feet  of  descent.  The  surface  water  of 
the  Great  Geyser  of  Iceland  Bunsen  found  to  have 
an  average  temperature  of  about  180°.  At  the 
depth  of  73  feet  the  temjierature  was  upwards  of 
250°.  This  high  temperature  is  probably  due  to 
the  same  causes  as  produce  the  heat  of  volcanoes. 

Gey'Sers  occur  in  volcanic  regions,  and  within 
limited  areas.  The  most  noted  are  those  of  Ice- 
Lind,  the  Yellowstone  National  Park,  and  New 
Zealand. 

The  region  wheie  they  are  cliiefly  found  in  Iceland  is 
about  two  miles  square.  Within  this  space  are  nearly  one 
hundred  openings  or  geyser  mouths  piercing  the  ground. 

Deeeription. — The  mouths  of  geysers  are  surrounded  with 
rims  of  variously  coloi-ed  incrustations.  These  rims  vary 
in  size  from  a  few  inches  to  many  feet  in  diameter.  That 
of  the  Great  Geyser  is  fifteen  feet  in  height,  and  fifty-six 
feet  in  diameter.  In  the  centre  of  this  monstrous  basin  is  a 
pipe  or  funnel  eight  feet  wide.  Out  of  this  funnel  boil- 
ing   water    constantly   issues.     Ei-uptive    discharges    also 


occur.  There  are  certain  premonitions  when  these  are 
about  to  take  pla(ic.  At  intervals  of  a  few  hours  under- 
ground rumblings  are  heard  :  the  water  in  the  basin  boils 
furiously,  and  jets  of  hot  water  with  clouds  of  steam  are 
thrown  up  to  tlie  height  of  several  feet. 

Several  of  these  intermittent  discharges  occur,  and  tlien 
succeeds  a  grand  eruption.  With  a  rumbling  that  shakes  the 
ground,  a  huge  column  of  lioiliiig  water  150  or  200  feet  high 
is  forced  up  into  the  air  with  loud  explosions  and  amid 
clouds  of  steam.  The  basin  and  pipe  are  thus  emptied  of 
water.  But  at  once  they  begin  to  fill  up,  only  tt)  be  emptied 
again  by  another  grand  explosion. 

Of  the  Yellowstone  Geysers  an  observer  says  : 

Of  all  the  geysers  whose  eruptions  we  witnessed,  the 
Grand  was,  I  think,  the  most  interesting.  It  played  each 
evening  at  a  regular  hour.  Suddenly,  with  a  single  prefa- 
tory spurt,  it  shot  a  vast  stream  of  water  over  two  hundred 
feet  into  the  air.  This  was  maintained  for  a  few  minutes 
with  unabated  vigor  ;  then  it  suddenly  ceased,  and  the 
waters  shrank  back  out  of  sight  into  the  cavernous  hollow 
below.  Meanwhile  subterranean  thunder  shook  the  ground. 
After  a  minute's  cessation,  tlie  geyser  again  burst  forth  with  ' 
even  greater  violence.  This  continued  until  nine  successive 
pulsations  had  occurred. 

Volcanoes  are  the  most  striking  of  all  mani- 
festations of  the  earth's  internal  heat.  They  are 
so  important  that  they  will  be  considered  in  de- 
tail in  a  subsequent  lesson.  Here,  however,  it  is 
proper  to  observe  what  strong  confirmation  they 
afford  to  the  theory  of  central  heat.  Streams  of 
lava,  white-hot,  like  molten  iron,  issue  through  their 
craters  from  the  interior  of  the  earth. 

^2.  Condition  of  the  Interior  of  the 
Martlt. — The  phenomena  above  noticed  have  sug- 
gested the  conclusion  that  the  interior  of  the  earth 
is  in  a  fluid  condition,  and  that,  consequently,  only 
to  the  depth  of  about  thirty  or  forty  miles  is  the 
crust  of  the  earth  solid. 

It  is  argued  that  if  the  heat  goes  on  increasing 
as  the  centre  of  the  earth  is  approached,  at  the 
same  rate  as  it  does  in  mines,  then  at  a  comparatively 
shallow  depth  even  the  most  refractory  substances 
must  necessarily  be  in  a  state  of  fusion. 

Many  philosophers,  however,  doubt  the  fluidity 
of  the  central  mass,  and  admit  the  existence  of  only 
local  seas  and  lakes  of  molten  rock.  They  contend 
that,  instead  of  being  fluid,  the  interior  of  the 
earth,  though  intensely  hot,  is  past}',  or  even  solid. 

In  justification  of  this  view  they  argue  that  the  enormous 
pressure  exerted  upon  the  interior  of  the  earth  would  Lullify 
the  effect  of  its  internal  heat,  because,  if  a  substance  is  sub- 
jected to  pressure,  it  cannot  melt  as  readily  as  under  ordinary 
circumstances.  A  body,  therefore,  may  remain  solid  at  a 
very  high  temperature,  if  it  be  under  pressure.  Of  course, 
the  condition  of  the  successive  layers  that  constitute  the 
substance  of  the  earth  is.  that  wliile  they  are  subjected  to  a, 
heat  wliicli  increases  enormously  as  the  centre  is  approached, 
they  are  at  the  same  time  subjected  to  a  pressure  which  also 
increases  enormously  as  the  centre  is  approached. 


VOLCANOES. 


Whether,  however,  we  adopt  the  viow  that  the  central 
mass  is  fluid  or  solid,  it  does  not  affect  the  foneliision  that 
it  is  in  an  intensely  heated  condition. 

TOPICAL   ANALYSIS. 
IV.    INTERNAL    HEAT   OF   THE   EAUTII. 

1.  Evidences  of  Internal  Heat. 

Mines,  Tncri'ase  of  huat  willi  tliptli.  Means  of 
miligatinj;  the  heat.     Depth  of  mines. 

Artesian  Wells.  Depth  readied.  Increase  of  tem- 
perature with  depth.     Distribution  of  such  wells. 

Hot  Springs.  Number  and  distribution.  Tempera- 
ture. 

Geysers.  Location.  Most  noted  geyeers.  Geyser 
basins.  Action  of  the  geyser.  Geysers  of  the 
Yellowstone. 

Volcanoes,    llow  they  indicate  internal  heat. 

2.  Condition  of  the  Interior  of  the  Earth. 

Two  views  held.  Argumi.nt:^  ill  favor  of  them. 
General  conclusion. 

Test  Questions.— Why  can  miners  not  work  deeper  below  the  sur- 
face than  about  2,500  feet  ?  Why  should  artesiun  wells  be  colder  than 
mines,  at  the  same  depth  ?  Why  are  rims  formed  round  geyser  basins  ? 
What  force  is  it  that  drives  out  the  water  to  such  a  height?  What  do 
we  infer  from  the  existence  of  geysers  in  any  region  ? 

V.  VOLCANOES. 

1.  A  Volcano  is  usually  a  mound,  hiJl,  or 
mountain,  formctl  of  materials  thrown  up  from 
the  interior  of  the  earth.  Its  most  important 
feature  is  the  crater,  a  de^sression  or  hollow, 
shaped,  as  the  name  imi^lies,  like  a  vast  bowl  or 
basin.  It  is  either  upon  the  summit  or  ni^on  the 
slopes  of  the  volcanic  mountain.  Through  a  hole, 
or  holes,  in  the  bottom  or  the  sides  of  the  crater, 
the  materials  ejected  find  their  way. 

Example. — The  crater  of  Kilauea,  in  Hawaii,  is  one  of  the 
most  remarl^able  in  the  world.  It  is  a  vast  oval  basin  about 
1,01)0  feet  deep,  one  mile  wide,  and  three  in  length.  Its 
floor  is  partly  occupied  by  two  lakes  of  molten  matter  in  a 
state  of  violent  ebullition.  .  Fiery  jets  are  sometimes  thrown 
from  the  surface  to  the  height  of  seventy  feet. 

2.  Formation  of  a  Volcano.— At  the  be- 
ginning of  its  existence,  a  volcano  is  simj^ly  a  hole 
in  the  crust  of  the  earth.  Materials  are  ejected. 
These  naturally  fall  around  the  sides  of  the  vent, 
and  form  a  circular  mound.  Successive  eruptions 
occur.  The  mound  becomes  larger  and  loftier  with 
each  eruj^tion,  until  in  the  course  of  centuries  a 
mountain  is  formed.  The  vent  remains  low  while 
the  matter  ejected  is  thus  built  up  about  it,  and  in 
this  way  the  crater  assumes  its  basin-like  shaije. 

Eapidity. — The  process  of  formation  is  some- 
times very  rapid.  Jorullo,*in  Mexico,  was  thrown 
up  in  a  single  night  to  the  height  of  l,fi9.5  feet 
above  the  plain  in  which  it  stands.     Monte  Nuovo, 


;i,  volcanic   hill    near  Naples,  was  formed  in    the 
course  of  a  few  days. 

Submarine  Volcanoe.s. — The  formation  of  a 
volcano  may  begin  at  considerable  de])ths  below  the 
level  of  the  sea.  In  proof  of  this  it  may  be  said 
that  vast  numbers  of  oceanic  islands  owe  their  ex- 
istence to  volcanic  action,  and  recent  deep-sea 
soundings  show  that  many  of  the  deoi)est  parts  of 
the  ocean  are  covered  with  volcanic  debris. 

In  1831  a  mass  of  matter  rose  from  the  sea  near  the  coast 
of  Sicily,  and  attained  in  a  few  weeks  the  height  of  170  feet 
above  the  water.  It  was  named  Graham  Island.  In  a  few 
months  it  disappeared,  because  the  materials  composing  it 
were  so  loosely  held  together.  If  the  matter  ejected  by  sub- 
marine volcanoes  is  compact,  a  permanent  island  is  formed. 

In  the  year  1700  a  volume  of  steam  was  seen  to  arise  from 
the  sea  about  thirty  miles  north  of  UnaUiska,  one  of  the 
Aleutian  Islands.  Ejected  materials  gradually  accumulated. 
The  mass  grew  higher  and  higher,  until  now  it  is  several 
thousand  feet  above  the  sea  level,  and  has  a  circumference 
of  two  or  three  miles. 


COTOPAXI. 

The  form  of  Volcanic  Mountains  is  gener- 
ally more  or  less  conical.  If  the  materials  ejected 
are  in  a  fluid  state,  the  elevation  is  comparatively 
small.  The  volcanoes  of  the  Sandwich  Islands 
present  the  form  of  exceedingly  flattened  cones. 
This  is  because  the  matter  which  they  emit  is  very 
liquid.  "When  the  materials  are  less  fluid,  the 
slopes  are  steeper,  and  the  form  of  the  mountain 
approaches  that  of  a  pointed  cone. 

A  notable  exami^le  is  Cotopaxi.  It  is  the  most 
.symmetrical  of  volcanoes. 

The  Height  of  Volcanoes.— The  highest  vol- 
cano in  the  Old  World  is  Klintchevskaia,  in  Kamt- 
chatka.  It  is  16,513  feet  high.  There  are  some 
in  South  America  higher  than  this.   Several  among 

the  Andes   have  an  altitude  of  more  than  20.000 
feet. 

3.  The  materials  ejected  from  volcanoes 


i6 


VOLCANOES. 


are  steam,  gases,  miul,  lava,  or  molten  rock,  stones, 
ashes,  sand,  and  dust. 

Lava  is  a  mixture  of  various  rocky  substaiiccs. 
The  most  important  of  its  elements  is  silica,  which 
is  familiar  to  us  in  the  forms  of  white  sand,  quartz, 
and  flint.  Issuing  from  the  volcano  lava  closely 
resembles  the  slag  of  a  smelting  furnace. 

Formation  of  Lava. — It  may  bo  askcfl  how  we  account 
for  its  fluid  condition,  if  we  .suppose  that  the  materials  in 
the  interior  of  the  earth,  thougli  intensely  hot,  are  still 
solid.  J'lio  explanation  is,  that  these  solid  but  intensely 
heated  materials,  on  being  driven  upward,  are  relieved  from 
pressure,  and  assume  the  fluid  state,  even  before  reaeliing 
the  surface. 

When  steam  bubbles  are  imprisoned  in  molten 
lava  in  the  act  of  cooling,  the  lava  is  converted 
into  a  light  porous  mass,  which  is  tlie  well-known 
substance  called  ^M?ft?ce. 

Often  the  lava  is  completely  reduced  to  powder, 
and  it  is  then  called  volcanic  ashes,  or,  if  coarser, 
volcanic  ,^and.  Sometimes  the  wind  blows  the 
molten  lava  into  delicate  fibres  like  tho.se  of  spun 
glass.*  The  Sandwich  Islanders  gave  the  name  of 
"  Pele's  Hair  "  to  this  substance,  Pele  being  the 
name  of  the  goddess  of  the  volcano  of  Kilauea. 


VOLCANO  uF  &ANTORLNI  (in  Grecian  Arcliipelago,  active  in  1866). 

;  4.  Qnantity  of  Matter  Ejected.— Tha 

quantity  of  lava  and  other  matter  emitted  by  vol- 
canoes is  immense.  Tlie  lava  that  issued  from 
Ilecla  in  1783  was  computed  by  Sir  Charles  Lycll 
to  be  equal  in  volume  to  the  water  discharged  by 
the  Mississippi  in  three  months. 


*  A  similar  j^nbstance  is  artificially  ])roduced  by  directing  a  blast  of 
nir  or  ateam  into  the  slag  of  a  smelting  furnace.  It  is  known  in  com- 
merce as  mineral  wool. 


In  the  eruption  of  Vesuvius,  a.d.  79,  the  mat- 
ter vomited  forth  far  exceeded  the  entire  bulk 
of  the  mountain  ;  while  in  16C0  Etna  disgorged 
twenty  times  its  own  mass. 

In  1878  such  quantities  of  jmmice  were  thrown 
out  of  the  volcanoes  of  the  Solomon  Isles  into  the 
surrounding  sea  that  it  took  ships  three  days  to 
force  their  way  througli  them.  Sometimes  one 
may  even  walk  upon  the  floating  pumice  as  ujion 
a  vast  raft. 

.7.  Voleanoe.<i  Classified. — Volcanoes  may 
be  classified  as  active,  dormant,  or  extinct.  Active 
volcanoes  eject  various  substances.  When  no  signs 
of  activity  are  given  for  a  considerable  time,  the 
volcano  is  said  to  be  dormant.  When  a  volcano 
has  been  dormant  for  centuries,  and  it  seems  prob- 
able that  its  activity  is  lost  forever,  it  is  said  to  be 
extinct. 

Tlie  frequency  of  volcanic  discharges  is  varied. 
Some  volcanoes  arc  continuously  active.  Stromboli 
has  been  for  2,000  years  in  a  state  of  constant,  but 
not  dangerous  activity.  It  is  visible  at  night  to  a 
distance  of  more  than  100  miles  all  round.  A  red 
glow  is  seen  from  time  to  time  above  the  summit 
of  the  mountain.  This  becomes  gradually  more 
and  more  brilliant,  and  then  as  gradually  dies  away. 
It  is  this  phenomenon  which  has  given  to  Strom- 
bolif  the  name,  "  Lighthouse  of  the  Mediterra- 
nean. " 

On  the  other  liand,  Cotopaxi  and  Tunguragua 
in  the  Andes  have  had  eruptions  only  once  in  100 
years. 

Vesuvius  exhibits  great  irregularity.  It  had  been  long 
dormant  before  the  eruption  of  a.d.  79.  Its  crater  was 
nearly  filled  up,  and  was  occupied  by  an  abundant  forest- 
growtli.  Cities  and  villages  graced  its  slopes.  After  this 
eruption,  none  of  great  moment  occurredr  until  1631.  At 
that  time,  one  of  the  most  destructive  on  record  took  place. 
It  continued  for  three  months,  and  destroyed  a  number  of 
cities  and  villages.     The  last  eruption  occurred  in  1872. 

From  these  and  similar  facts,  it  is  evident  that  we  have 
no  knowledge  of  any  law  which  governs  the  frequency  of 
volcanic  eruptions. 

0.  EvHXttions. — There  is  no  definite  order  in 
which  the  phenomena  of  an  eruption  succeed  one 
another.  They  are  usually  jjreceded  by  subterra- 
nean rumblings  and  tremors.  Before  the  great 
eruption  of  1872,  Vesuvius  gave  indications  of  un- 
usual activity  for  a  whole  year.  In  many  cases, 
however,  the  eruption  follows  the  warning  imme- 
diately. An  eye-witness,  writing  of  Stromboli, 
says  that  he  had  observed  numerous  light,  curling 
wreaths  of  vapor  ascending  from  the  crater  ;  then 


t  This  fire,  it  should  be  observed,  is  really  the  reflection  upon  the 
vapor-cloud  from  the  seething  surface  of  the  red-hot  lava  within  the 
crater. 


VOLCANOES. 


17 


suddenly,  without  the  slightest  warning,  a  sound 
was  lieard  like  that  of  a  locomotive  giving  ofl' 
steam  ;  and  the  eruption  at  once  occurred. 

Emission  of  Steam. — In  general,  after  the  pre- 
liminary rumblings  and  tremors,  dense  columns 
and  globular  masses  of  watery  vapor  mingled  with 
a  variety  of  gaseous  substances  issue  from  the 
crater.  According  to  the  state  of  the  atmosphere, 
and  the  existence  of  winds  and  air  currents,  the 
vapor  assumes  a  variety  of  forms. 

In  the  case  of  Mount  Vesuvius  it  not  unfre- 
qucntly  expands  after  attaining  a  certain  height, 
and  becomes  like  a  vast  "  umbrella,"  as  the  Ital- 
ians call  it,  having  atop  many  miles  in  circumfer- 
ence. The  lurid  glare  of  the  boiling  lava  in  the 
crater  below  is  reflected  upon  the  under-surface  of 


tricity.     A  machine  has  been  constructed  to  generate  elee 
tricity  in  this  way.     From  it  torrents  of  sparks  as  mucli  aa 
fourteen  inolies  in  lengtli  have  been  obtaineil.     The  crater, 
witli  itsimmense  volume  of  uprising  vapor,  may  be  coniparoci 
to  a  gigantic  machine  of  tiiis  description. 

Emissiox  of  Solid  Matkrials. — Often  with  the 
vapor  are  mingled  immense  quantities  of  volcanic 
ashes  and  sand,  which  descend  and  cover  the  sur- 
rounding country,  sometimes  to  the  depth  of  many 
feet. 

Eighteen  hundred  years  ago  (a.d.  79),  the  cities 
of  Herculaueum  and  I'ompeii  in  Italy  were  cov- 
ered with  a  deluge  of  ashes  from  au  eruption  of 
Vestivius.  Tliey  were  buried  from  TO  to  120  feet, 
and  lost  to  view  for  nearly  seventeen  centuries.  In 
1711,  a  well-digger  turned  up  a   bit  of  statuary 


VESUVIUS    IN    ERUPTION,    AS    SEEN     FKU.M    NAPLES.    APRIL    26.    187^. 


the  umbrella,  and  gives  the  appearance  of  a  vast 
conflagration.  This  spectacle  is  indescribably  im- 
])ressive  at  night.  During  the  eruption  of  Vesu- 
vius in  1872,  instantaneous  photographs  were 
obtained  of  the  umbrella.  The  above  cut  is  a  copy 
of  one.  From  this,  recollecting  that  Vesuvius  is 
4,000  feet  high,  we  see  that  the  vapor  rose  to  the 
height  of  20,000  feet,  or  nearly  four  miles. 

The  vapor  emitted,  being  condensed,  falls  as  rain. 
The  rainfall  is  excessive  and  long  continued,  and 
often  gives  rise  to  destructive  floods.  Around  the 
vapoiy  column  vivid  lightning  constantly  plays. 

Jets  of  steam  under  high  pressure,  if  allowed  to  issue  from 
an  orifice,  give  rise,  in  doing  so,  to  large  quantities  of  elec- 


which  led  to  the  discovery  of  the  two  cities.     The 
work  of  exhuming  them  is  still  going  on. 

The  distance  to  which  the  ashes  of  a  volcano  may  be  car- 
ried is  almost  incredible.  In  184."),  the  ashes  of  Hecla  were 
carried  to  the  Orkney  Islands,  a  distance  of  nearly  700  miles, 
and  in  1813.  those  of  Tomboro.  in  the  island  of  Sumbawa, 
fell  at  Beneoolen,  1,100  miles  away. 

Rocks  and  stones  are  sometimes  vomited  forth 
with  fearful  noise,  and  hurled  with  prodigious 
force.  A  mass  of  rock,  measuring  300  cubic  feet, 
was  on  one  occasion  thrown  from  Cotopaxi  to  a 
distance  of  about  eight  miles. 

The  Emission  of  Lava  in  the  molten  state  is  the 
most  imposing  of  volcanic  phenomena.      The  ac- 


i8 


VOLCANOES. 


tion  which  goes  on  has  beeu  compared  to  that  which 
occurs  in  a  pot  of  boiling  porridge. 

Explanalion. — As  the  mass  of  porridge  gets  hot,  steam  is 
generated  in  it  at  the  bof  torn.  Tliis  rises  tlirough  the  por- 
ridge. In  doing  so  it  forces  a  jjortion  upward.  More  and 
more  steam  being  generated,  bubbles  of  i)orridge  rise  to  tlie 
surface,  and  mimic  explosions  occur,  or  the  porridge  is 
thrown  in  little  jets  above  the  surface  of  the  boiling  mate- 
rial. The  process  may  increase  in  violence  until  the  phe- 
nomenon of  boiling-over  takes  place.  Quite  similarly  the 
boiling  lava  is  forced  upward  higher  and  higher  in  its  crater 
by  vast  volumes  of  steam  tliat  are  seeliing  to  escape.  Ex- 
plosions occur  on  the  boiling  surface,  and  often  jets  are 
thrown  far  up  into  the  air. 

Finally,  the  rising  lava  overflows  the  rim  of  the  crater,  or 
quite  as  often  bursts  through  the  sides  of  the  mountain,  and 
pours  down  its  slopes  in  rivers  of  fire. 

So  numerous  were  the  fissures  which  rent  Vesuvius  in  the 
eruption  of  1872  that  liquid  lava  seemed  to  ooze  from  every 
portion  of  it,  and,  as  an  eyewitness  expressed  it,  "Vesuvius 
sweated  fire." 

Lava  Streams  vary  in  magnitude.  The  hirg^ 
est  recorded  were  those  of  Skaptar  Jokul,  in  Ice- 
land, in  the  years  1783-5.  Torrents  of  molten 
rock  deluged  the  island.  River-courses,  ravines, 
and  lakes  were  filled,  and  the  surface  of  the  coun- 
try for  hundreds  of  square  miles  was  completely 
devastated.  Some  of  the  streams  were  about  fifty 
miles  in  length,  and  in  certain  places  fifteen  miles 
in  breadth,  and  100  feet  deep.  In  some  of  the 
naiTow  valleys  the  depth  was  600  feet. 

The  velocity  of  the  streams,  and  the  distance  to 
which  they  reach,  depend  on  the  fluidity  of  the 
lava,  and  the  slope  of  the  land.  One  thousand 
feet  per  hour  is  a  rapid  rate  ;  the  extreme  of 
ten  thousand  feet  ])er  liour  has  been  observed, 
though  rarely. 

The  retention  of  its  heat  bj'  a  lava-stream  is  very 
remarkable.  When  the  surface  of  the  stream  has 
cooled,  it  becomes  a  hard  crust  which  prevents  the 
escape  of  the  heat. 

A  mass  of  lava  500  feet  tliick,  ejected  from  Jondlo  in  1759, 
was  seen  smoking  by  Alexander  von  Humboldt  forty-five 
years  after.  The  Indians  lit  cigars  at  its  crevices.  The  lava 
thrown  from  Vesuvius  in  1858  continued  as  late  as  1.S7.3  to 
give  out  steam,  and  remained  so  hot  that  one's  hand  could 
not  be  held  in  some  of  the  fissures  for  more  than  a  few 
seconds. 

ExD  OF  Eruptiox. — Tlie  flow  of  tlie  lava  is  the 
beginning  of  the  end.  After  its  occurrence  the 
showers  of  ashes  gradually  cease,  the  e.xplosions 
become  less  and  less  frequent,  and  at  length  no 
evidence  of  volcanic  activity  remains,  save  perhaps 
a  vapor-cloud  veiling  the  summit  of  the  mountain. 

V      7.  Distrihution    of    Volcnitoes.  —  Two 

significant  facts  are  to  be  observed  regarding  the 
distribution  of  volcanoes. 

First  :  the  active  volcanoes  of  the  globe  are,  as  a 


rule,  situated  i/pon  areas  which  are  undergoing 
uphenval.  'I'hose  jiortioiis  of  the  surface  of  the 
earth  which  are  sub.siding  are  without  volcanic 
activity. 

Second  :  almost  all  volcanoes  are  near  the  gea. 
Tliose  upon  the  continents  are  close  to  tlie  shores. 
The  only  well-authenticated  examples  of  volca- 
noes situated  far  inland,  are  the  active  volcanoes  of 
Boschan  and  Turfaii,  or  Hot-Schen,  and  the  Sol- 
fatara  of  Urumtsi,  all  in  Central  Asia. 

The  mo.st  striking  exemplification  of  tliis  law  of  volcanic 
distribution  is  presented  by  the  Pacific  Ocean.  It  is  literally 
encircled  with  active  volcanoes. 

The  great  Volcanic  Belts. — There  are  three 
great  belts  traversing  the  globe,  within  which 
nearly  all  tlie  volcanoes  of  the  world  are  situated. 
These  may  be  called  the  Pacific  Insular  Belt,  the 
Atlantic  Insular  Belt,  and  the  American  Conti- 
nental Belt.     [See  map  on  ojiposite  page.] 

llie  Pacific  Insular  Belt  extends  ail  along  the 
northern  and  western  shores  of  the  Pacific  Ocean. 
Beginning  with  the  Aleutian  Islands  it  embraces 
Kamtchatka,  theKurile,  Jajiancse  and  Philippine 
Islands,  Sumatra,  Java,  New  Guinea,  the  Friendly 
Islands,  and  New  Zealand. 

One  extension  of  this  belt  embraces  the  Society,  Marquesas 
and  Sandwich  Islands  ;  another  is  the  volcanic  region  of 
Victoria  Land. 

The  Atlantic  Insular  Belt  comprises  extinct  and 
active  volcanoes  and  volcanic  islands  which  trav- 
erse the  Atlantic  from  north  to  south.  The  Isl- 
ands of  Jan  Mayen,  Iceland,  the  Azores,  Cape 
Verd  Islands,  St.  Helena,  and  Tristan  d'Acunha, 
are  points  which  mark  this  volcanic  band. 

Tlie  American  Continental  Belt. — The  third 
great  volcanic  belt  is  continental.  It  extends  from 
Cape  Horn  in  South  America,  to  Alaska  in  North 
America,  a  distance  of  more  than  10,000  miles. 
All  along  this  line  volcanoes,  singly  or  in  groups, 
are  found.  An  outlying  spur  of  it  includes  the 
West  Indies. 

A  minor,  yet  very  important  volcanic  belt  is  that  of  the 
Mediterranean  region.  It  comprises  Etna,  Vesuvius, 
Stromboli,  and  Vulcano  in  the  Lipari  Islands,  and  Santorini 
and  Nisyros  in  the  .^gean  Sea. 

Outside  of  the  three  great  belts  there  are  many 
volcanoes  irregularly  distributed.  In  the  Pacific 
all  islands  not  of  coral  origin  are  composed  of  vol- 
canic rocks.  In  the  Indian  Ocean  there  are  vol- 
canoes upon  Madagascar  and  the  adjacent  islands. 

In  Central  France,  in  Spain,  and  generally 
throughout  Europe,  there  are  numberless  proofs 
of  volcanic  action.  Africa  contains  about  ten 
active  volcanoes.  The  most  remarkable  for 
the  irregularity  of  their  situation  are  those  in 
Central  Asia  already  mentioned. 


ira 


VOLCANOES. 


The  number  of  Active  Volcanoes  on  tlie  sur- 
face of  tlie  globe  is  cstimutcd  at  from  300  to  350. 
Of  dormant  and  extinct  about  700  are  reckoned. 


8.  The  most  active  Volcanic  Hegion  in 

the  world,  at  present,  consists  of  the  islands  in  the 
Malay  Archipelago.  Java  is  the  centre  of  it.  No 
region  is  so  thickly  studded  with  burning  moun- 
tains as  this  island.  It  lias  twenty-one  volcanic 
cones. 

In  1773  one  of  them  was  in  violent  eruption.  Its  immense 
cone  actually  disajipeared.  It  carried  down  with  it  ninety 
square  miles  of  land,  and  forty  villages  were  swallowed  up. 

In  1815,  Tomboro,  on  the  island  of  Sumliawa,  300  miles 
from  Java,  burst  forth  with  sueh  violence,  that  the  explo- 
sions were  heard  at  the  distance  of  970  miles. 


i 


9.  Causes  of  Volcanoes. — The  fundamen- 
tal cause  of  volcanic  action  is  undoubtedly  the  ex- 
pansive force  of  compressed  steam  and  other  gases. 
Two  cases  are  conceivable  :  (1)  the  compressed 
steam  and  gases  may  be  free,  {.  c.  not  blended 
with  the  lava  ;  or,  (2)  they  may  be  imprisoned 
within  the  substance  of  the  lava.  The  force 
developed  will  be  the  same  in  both  these  cases,  but 
the  mode  of  action  will  be  somewhat  difEerent.  Let 
us  consider  the  first  ease. 

Action  of  Free  Gases. — Bear  in  mind  that  at 
a  comjiaratively  shallow  depth  the  earth  is  intense- 
ly hot.  Then  observe  that  water  may  readily  find 
its  way  through  crevices  or  between  the  strata  of 
rocks,  and  come  in  contact  with  the  heated  mat- 
ter. The  eifect  will  be  to  convert  a  portion  of  the 
inflowing  water  into  steam.  This  may  be  done 
with  great  suddenness. 

The  same  conditions  will  occur  as  those  which 
often  cause  the  explosion  of  a  steam  boiler.  The 
water  in  the  boiler  gets  low,  the  fire  is  kept  up, 
and  the  walls  of  the  boiler  become  intensely  heated. 
If  now  there  be  a  sudden  influx  of  water,  some  of 
it  is  converted  into  steam  with  such  rapidity  and 
in  such  quantity  that  it  cannot  possibly  escape. 
The  boiler  is  unable  to  resist  the  pressure,  and  an 
explosion  takes  place. 

Similarly  the  water  that  finds  its  way  into  the 
intensely  heated  interior  of  the  earth  may  be  sud- 
denly converted  into  steam.  The  expansive  force 
of  the  steam  increases  under  the  two  influences  of 
enormous  heat  and  enormous  pressure. 

Suppose  the  water  to  enter  some  subterranean  cavity 
partly  filled  with  molten  lava.  Steam  is  suddenly  gen- 
erated and  an  explosion  occurs.  By  the  concussion,  the  fis- 
sure which  admitted  the  water  is  closed,  and  the  I'einaining 
water  completely  pent  up.  It  is  converted  into  steam. 
Heavy  pressure  and  intense  heat  give  to  it  enormous  expan- 
sive fiower.  We  can  imagine  how  such  superheated  steam 
might  drive  upward  lava,  or  stones  and  sand.  It  would  act 
on  exactly  the  same  principle  as  that  of  the  compressed  air 
in  the  air-chamber  of  a  force  pump  or  a  water-ram. 


Action  of  Absorbed  Gases. — The  second  case 
in  all  probability  occurs  more  commonly  than  the 
first,  and  in  fact,  it  seems  to  contain  the  explana- 
tion of  nearly  all  the  phenomena  of  volcanic  eru])- 
tions.     A  number  of  substances,  solid  and  li<juid, 
absorb,  under  pressure,  and  at  high  temperatures, 
many  times  their  own  volume  of   steam  and  other 
gases.     If   the   temperature   be    reduced,    or    the 
pressure  be  relieved,  these  gases  can  no  longer  be 
retained  in  absorption.     They  escape  with  explosive 
violence.     Lava,  intensely  heated  and  under  press- 
ure, absorbs   many  times  its  volume  of  steam  and 
other  gases.     Imagine  it  thus  charged  to  be  forced 
upward  through  the  crust  of  the  earth.     Its  cajiac- 
ity  for  retaining  gases  in  absorjition  is  diminished. 
The  liberated  gas  expands  and  forces  the  lava  in 
whatever  may  be  the  direction  of  least  resistance, 
precisely  as  the  volume   of  gases   liberated   from 
gunpowder  and   similar  substances   expands   and 
forces  obstacles  before  it  with  explosive  violence. 

Among  other  things  this  satisfactorily  explains 
the  pulverization  of  lava  and  the  production  of 
volcanic  sand.  The  gases  absorbed  by  the  lava 
being  relieved  from  pressure  blow  it  into  atoms,  as 
wood  is  blown  to  pulp  in  a  well  known  process  for 
making  paper. 

The  above  theory  that  volcanic  action  is  mainly  due  to  the 
expansive  force  of  steam  derives  confirmation  from  the  fact 
that  volcanoes  are  in  general  situated  close  to  the  sea. 

TOPICAL  ANALYSIS. 
V.    VOLCANOES. 

1.  Description. 
Principal  feature.    Crater  of  Kilauca. 

2.  Formation. 

Mode.  Rapidity  of  formation.  Submarine  vol- 
canoes. Formof  volcauicmoiintains.  Height  of 
volcanoes. 

3.  Materials  ejected. 

Luva.  Formation  of.  Pumice.  Volcanic  ashea 
and  sand.    Pele'e  hair. 

4.  Quantity  of  matter  ejected. 
Exumplt's. 

5.  Volcanoes  classified. 

Frequency  of  discharge.    Examples. 

6.  Eruptions. 
Phcnomcnii  of.  Appearance  of  flame,  how  pro- 
duced. Cause  of  lightning.  Emission  I'f  solid 
materials.  Emission  of  lava,  how  produced.  Lava- 
streams,  magnitude  and  velocity  of.  Retention 
of  heat  by-    End  of  eruption. 

7.  Distribution  of  volcanoes. 

In  relation  to  change  of  level  of  snrrounding  area. 
In  relation  to  the  sea.  Great  volcanic  belts.  Pacific 
Insular.  Atlantic  Insular.  American  Continental. 
Minor  belt.  Irregtdarily  of  distribution.  Num- 
ber of  active  volcanoes. 


EARTHQUAKES. 


21 


8.  Most  active  volcanic  region. 

situation. 


9.  Cause  of  volcanoes. 

ConceiVHl)Ic'  cases, 
absorbed  fjases. 


Action  of  free  gases.    Action  of 


Test  Questions.— In  what  way  would  yon  suppose  tlie  ininibcr  of 
active  volcanoes  to  l)e  clninging,  and  why  ?  What  volcano  is  nearest  to 
th*j  place  where  yon  live  J* 


VI.  EARTHQUAKES. 

1.  An  Earthquiihe  is  a  shakiny  or  trem- 
bling of  some  part  of  tlie  crust  of  the  earth.  It  i.s 
a  vibratory  or  ■wave-like  inotion  resenibliug  tlie 
grouud-swell  or  roll  of  the  sea.  It  may  be  uothing 
more  than  a  slight  tremor  like  that  made  by  a 
loaded  wagon  passing  along  a  street,  or  it  may  be 
such  a  violent  movement  as  to  desti-oy  whole  cities. 

Usually,  at  the  commencement  of  an  earthquake, 
a  rumbling  noise,  like  distant  thunder,  deep  down 
below  the  surface  of  the  earth,  is  heard  travelling 
along,  as  if  in  search  of  some  weak  place  through 
which  to  burst.  Then  suddenly,  without  any 
warning,  the  ground  rises  and  falls,  houses  rock 
to  and  fro,  until  they  are  rent  from  top  to  bottom, 
or  fall  with  a  crash  into  ruins.  In  some  cases  the 
earth  ojiens  with  gaping  cracks  wliich  either  close 
again  or  are  permanent.  In  a  few  seconds  a  city 
may  be  demolished,  and  hundreds  or  thousands  of 
its  inhabitants  may  be  dead  or  dying. 

The  origin  of  the  vibratory  motion  or  earth- 
wave  is  called  the  centre  or  focus.  It  is  not  a 
point,  but  a  fissure  or  space  between  great  masses 
of  rock.  It  is  believed  that  it  is  rarely  more  than 
thirty  miles  below  the  surface. 


^^,^^_,,4^ 


Diagram  illustrating  the  propagation  of  an  earth-wave  from  F,  the  focus. 
V  is  a  point  where  the  shock  is  vertical ;  A,  a  town  where  the  shock  is  felt. 
If  we  know  A  V,  the  distance  between  A  and  V,  and  the  direction  of  the 
shock  at  A,  we  can  compute  V  F,  the  depth  of  the  focus. 

From  the  focus  the  earth-wave  \)i  propagated  in 
all  directions.  While,  however,  this  is  generally 
true,  it  must  be  observed  that  the  transmission  of 
the  vibration  will  necessarily  depend  on  the  nature 
of  the  materials  encountered.  In  some  directions, 
perhaps  in  many,  the  earth-wave  will  meet  with 
such  obstacles  that  it  will  rebound,  and  practically 
be  nullified,  like  a  wave  of  water  dashing  against 
a  rock. 

The  velocity  of  the  earth-wave  appears  to  be, 
on  an  average,  about  twenty-five  miles  a  minute. 
It  may  attain  the  enormous  speed  of  five  or  six 
thousand  miles  an  hour. 


2.  Duration  of  Earthquake,>i.—Vydtih- 

quakes  may  b^  momentary  ;  or  they  may  consist 
of  several  successive  shocks;  and  these  may  l)e 
repeated  during  long  periods.  After  the  earth- 
quake, which,  in  1760,  destroyed  the  city  of  Cu- 
mana,  in  Venezuela,  shocks  were  felt  nearly  everj' 
hour  for  fourteen  months. 

In  St.  Thomas,  after  the  eartlupiake  of  1807, 
and  at  Charleston,  after  that  of  1880,  shocks 
were  felt  for  many  weeks. 

3.  Area  of  Disturba/nce.  —  The  area 
through  which  the  disturbance  extends  may  be 
very  large.  The  shock  of  the  earthquake  of  Lis- 
bon, in  1755,  was  definitely  felt  as  far  as  Finland 
in  one  direction,  and  as  far  as  Madeira  in  another. 
[See  map,  page  19.] 

The  disturbance  affected  the  sea  to  a  much 
greater  distance.  The  water  rose  among  the  West 
India  Islands  so  that  Antigua,  Martinique,  Guade- 
loupe and  Barbadoes  were  overflowed.  The  area 
disturbed  was  four  times  as  great  as  that  of  Europe. 

In  1783.  all  the  towns  witliin  a  radius  of  twenty  miles 
from  the  town  of  Oppido,  in  Calabria,  were  destroyed. 

The  great  earthquake  of  Guadeloupe,  in  1842,  extentled 
through  the  distance  of  3,000  miles  in  a  direet  line,  and  S(ai- 
sibly  afiected  an  area  of  not  less  than  3,000,000  square  miles. 

Ix  SHAPE,  the  area  of  disturbance  is  commonly 
an  irregulitr  oval. 

4.  The  Sea-  Wares  which  are  caused  by 
earthquakes  that  have  their  centre  under  the 
ocean  bed,  are  appalling  phenomena. 

The  water  at  first  recedes  from  the  beach,  and 
exposes  the  sea-bed  even  beyond  the  usual  limits 
of  low  water.  Then  the  sea-wave  comes  in  with 
a  steej)  front  or  wall  sometimes  more  than  fifty 
feet  high.  It  drives  back  the  i-eceding  water, 
and  deluges  the  shore,  sometimes  demolishing 
whole  towns.  It  often  passes  inland  to  the  dis- 
tance of  several  miles.  The  inhabitants  rush  to 
the  hills,  and  remain  there  until  the  wave  sub- 
sides. 

Examples. — The  great  wave  of  the  Lisbon  earthtjiiake  was 
sixty  feet  high  at  Cadiz.  It  rose  anil  fell  eighteen  times  at 
Tangier,  in  Africa. 

In  1854,  when  Simoda,  in  Japan,  was  destroyed  by  an 
earthquake,  the  sea-wave  completely  overwhelmed  the  place. 
The  receding  wave  actually  crossed  the  Pacific,  and  made 
the  water  rise  on  the  coast  of  California. 

In  1746,  the  town  of  old  Calliio.  in  Peru,  was  destroyed  by 
an  earthquake.  A  wave  80  feet  high  tore  from  her  anchors 
a  Spanish  man-of-war,  lifted  her  over  the  houses,  and  carried 
her  several  miles  inland.  The  receding  wave  left  her  high 
and  dry  on  the  road  to  Lima. 

Sea-waves  are  often  perceptible  throughout  an  entire  ocean 
basin.  They  travel  across  the  Pacific  at  the  rate  of  about 
850  miles  an  hour. 


EARTHQUAKES. 


If  tho  cpntre  of  the  earthquake  is  on  land,  so  near  the 
coast  as  to  disturb  tlie  sea,  the  waves  produced  are  thrown 
out  from  tlio  slioro  and  are  harmless,  'I'his  explains  why, 
although  the  Charleston  earthquake  was  felt  at  sea  as  far  as 
the  Bermudas,  no  wave-damage  was  done  in  the  harbor  of 
Charleston. 

5.  Destructive  Effects. — Earthquakes  are 
perhaps  the  most  impressive  manifestations  of 
power  in  the  material  world.  Tlie  destructioji  of 
human  life  occasioned  by  them  is  appalling. 

On  the  1st  of  November,  1755,  Lisbon  was 
shaken  by  the  "great  eaj'thquake, "  and  in  six  min- 
utes its  palaces  were  in  ruins,  and  GO, 000  of  its 
inhabitants  were  dead. 

In  March,  ]81;i,  Caracas,  in  Venezuela,  was  de- 
stroyed, with  10,000  of  its  inliabitants. 

<i.  Ujtheavals  and  Dejiressions, — Geo- 
logical changes  of  great  importance  often  acconi- 
l)any  earthquakes. 

In  the  year  1819  an  earthquake  occurred  in  the 
region  adjacent  to  the  mouth  of  the  Indus.  It 
completely  destroyed  tlie  town  of  Bhooj,  and  was 
felt  within  a  radius  of  hundreds  of  miles.  A  tract 
to  which  the  natives  gave  the  name  of  "Allah 
Bund,"  or  "Mound  of  God,"  was  raised  where, 
before,  there  luxd  been  a  level  plain.  The  "Bund" 
was  fifty  miles  long,  sixteen  miles  wide,  and  about 
ten  feet  high.  At  tlie  same  time  the  fort  and  vil- 
lage of  Sindree,  with  the  neighboring  region,  sub- 
sided ;  the  sea  flowed  into  the  sunk  area,  and  an 
inland  sea  was  formed  covering  3,000  square  miles. 

7.  Distfibution  of  EarthquaUes. — Xo 

part  of  tlie  earth,  is  entirely  free  from  earth- 
quakes. In  certain  parts  of  Japan  tremors  are 
felt  every  day.  Vessels  not  unfrequently  rei^ort 
earthquake  shocks  at  sea. 

In  the  OLD  WORLD  they  are  most  frequent  in  a 
region  which  embraces  the  northern  shores  of  the 
Mediterranean  Sea,  and  extends  eastward  into  the 
central  portions  of  Asia. 

In  the  NEW  WORLD  earthquakes  are  far  more 
common  than  in  the  Old.  Both  the  eastern  and 
western  mountain  regions  of  North  America  are 
subject  to  them,  but  the  region  of  greatest  fre- 
quency is  in  South  America.  It  comprises  Ecua- 
dor, Peru,  and  Chili. 

In  many  places  within  this  region  the  houses  are  built  of 
reeds  and  bamboo,  lashed  by  thongs  of  bull's  hide,  and  se- 
cured in  their  places  with  cords  instead  of  nails,  that  they 
may  yield  to  the  shooks  without  being  shaken  to  pieces. 

The  natives  can  feel  the  approach  of  an  earthquake  long 
before  the  stranger  can.  Suddenly,  in  the  midst  of  gayety, 
the  author  has  heard  the  cry,  accompanied  by  shrieks, 
"Treinblor!"  {earthquake].  Then  a  rush  for  the  streets. 
Sometimes,  when  these  alarms  take  place  in  the  dead  of 
night,  the  whole  population  may  be  seen  out  in  their  night- 
clothes,  kneeling  and  praying  in  an  agony  of  teiTor, 


H.  Causes  of  Earthquakes.  —  Various 
causes  have  been  assigned  to  account  for  earth- 
quakes. Many  have  referred  them  to  volcanic 
action  ;  but  they  are  probably  due  for  the  most 
part  to  what  is  known  as  "  displacement." 

(1)  By  this  is  meant  the  sliding  of  vast  masses 
of  rock  one  upon  another.  AVhen  the  millstones 
in  a  grist  mill  are  in  motion,  the  whole  building 
is  in  a  state  of  vibration  or  tremor.  The  vibra- 
tions are  more  or  less  violent  according  to  the 
size  and  number  of  the  stones.  And  in  like  man- 
ner the  noise  or  rumbling  produced  will  vary. 
Now  imagine  that,  from  any  cause,  masses  of  rock 
millions  of  times  the  size  of  the  millstones  should 
slide  or  grind  upon  one  another.  Clearly  rum- 
blings and  tremors  would  be  occasioned.  We  can 
imagine  the  tremors  produced  by  the  sliding  of 
vast  rock  masses  to  be  so  violent  as  to  produce 
tlie  destructive  effects  of  earthquakes. 

But  can  any  cause  be  conceived  for  the  displace- 
ment supposed  ?  It  is  believed  tiiat  the  cooling 
and  contraction  of  tlie  interior  of  the  earth  ac- 
count for  it.  The  inner  strata  or  layers  of  rock; 
as  they  cool  and  contract,  shrink  away  from  the 
outer  layers.  Then  some  portions  of  the  outer 
layers  are  left  without  support.  They  may  now 
bend  or  they  may  break.  Having  broken,  tliey 
may  slide  and  grind  upon  the  rocks  tliat  lie  under- 
neath. The  effects  of  such  sliding  may  be  faintly 
illustrated  by  the  jarring  and  noise  produced  liy 
millstones  in  motion,  or  by  a  lieavy  body  of  snow 
when  it  slides  upon  the  roof  of  a  large  church. 

If  reference  be  made  to  page  28,  it  will  appear  that  the 
same  causes  which  are  believed  to  occasion  earthquakes  are 
considered  to  have  been  at  work  in  the  formation  of  the 
grand  mountain  systems  of  the  earth.  If  this  view  be  correct, 
then  where  mountain-making  goes  on,  earthquakes  should 
abound.     And  this  has  always  been,  and  is  the  case. 

(3)  While  thus  displacement  is  the  direct  cause 
of  earth(|uakes  in  general,  it  is  probable  that  cer- 
tain earthquakes,  which  have  been  termed  "ex- 
plosive," are  due  to  volcanic  action,  as  their  indi- 
rect cause.  These  are  of  minor  importance  and 
are  local  in  their  effects. 

9.  Helation  of  Earthquakes  to  Vol- 
canoes.— A  close  relation  exists  between  earth- 
quakes and  volcanoes.  Displacements  are  the 
direct  cause  of  earthquakes,  and  they  are  condi- 
tions which  at  least  contribute  to  the  production 
of  volcanic  action.  Hence  it  is  that  earthquakes 
are  most  frequent  in  volcanic  regions. 

Moreover,  aside  from  what  is  noted  above  in  paragraph  (2), 
volcanic  action  may  aid  in  the  production  of  earthquakes 
by  removing  matter  from  the  interior  of  the  earth,  and  de- 
positing it  upon  strata  already  under  strain.  This  would 
contribute  to  displacement,  and  so  to  earthquakes. 


TOPICAL  ANALYSIS  FOR  REVIEW. 


23 


TOPICAL  ANALYSIS. 
Vr.    KAllTirifUAKKS. 

1.  Description, 

Characteristic   pltenomcna.     Origin    of    vibratory 
motion  of  oarl!i-wavf.     Vclorlty  of. 

2.  Duration. 

Kxamples. 

3.  Area  of  Disturbance. 

Examples. 


4.  Sea-Waves. 

Description.    Kxamplce. 

5.  Effects. 

I)c.'*trnctlon  of  iinman  life. 

6.  Upheavals  and  depressions. 

Exjuiiples. 

7.  Distribution. 

Ill  goncnil.    Ill  till'  01(1  World.    In  the  New. 

8.  Causes  of  Earthquakes. 

9.  Relation  to  Volcanoes. 

As  to  locality,   cause  and   time  of  occurrence 


TOPICAL   ANALYSIS   FOR   REVIEW. 


The  Earth  as  a  Planet . 


What  i-s  the  Earth  ?      Ancient  Theory.      Copernican, 
The  Soliiv  System.      The  Sun.      Planets.      Nebular  Hypothesis. 
Actual  size  of  the  Earth. 
I     Comparative  Insignificance. 


The  Planetary  Movements. 


Effects  of  the  Earth's  Motions. 

Rotation. 

Revolution. 

Inclination  of  Planetary  Axes.       Results. 

Adaptation  of  the  Eiirtli  for  Human  Habitation. 


Magnetism  of  the  Earth 


IIow  Demonstrated. 

Magnets.      Natural.      Artificial.      Properties  of  the  Magnet 
The  Earth  a  Magnet. 
Inclination  of  the  Needle. 
Declination  of  the  Needle. 
Magnetic  Storms. 

Sun  Spots  and  Terrestrial  Magnetism. 
[     Cause'  of  Terrestrial  Magnetism.      Uses  of. 


Internal  Heat  of  the  Earth 


Evidences  of.      Mines.      Artesian   Wells,  Hot  Springs,  Geysers,   Volcanoes. 
Condition   of   the  Interior  of  the   Earth. 


Volcanoes 


Description   of.      Formation  of.      Rapidity.      Form. 

Materials   Ejected.      Kinds.      Quantity. 

Eruptions.      Most  Common   Phenomena.      Lava-streams. 

Distribution   of   Volcanoes.      Two   Laws.      Volcanic  Belts. 

Most   Active   Region. 

Causes  of   Volcanoes.      Action  of    Gases. 


Earthquakes. 


t     I     t 


Description.       Duration  of  Earthquake. 

Area  of  Disturbance. 

Sea   Waves. 

Destructive  Effects. 

Upheavals  and  Depressions.     Distribution  of  Earthquakea 

Causes   of    Earthquakes.      Relation    to  Volcanoes. 


^ttere<d  acccnUnti  i!o  .AiT  <^  Cciifpy;'. 


En^ra.yed  try  Edif4'W(iLer 


PART     I  I 


THE    LAND. 


I.  ARRANGEMENT  OF  LAND  MASSES. 

1.  Relations  of  land,  water  and  air. 

— In  the  preceding  pages  we  have  regarded  the 
Earth  as  a  whole.  In  those  which  are  to  follow 
we  shall  consider  (1)  the  various  constituents  of 
the  earth,  viz.,  the  land,  the  water,  and  the  air; 
(2)  the  phenomena  which  belong  to  each  of  these ; 
and  (3)  the  life  which  they  support. 

The  land,  the  water,  and  the  air  are  to  be  con^ 
sidered  as  parts  of  a  grand  and  most  i^erfect  mech- 
anism. They  contribute  in  a  variety  of  ways  to 
the  maintenance  of  plant  and  animal  life. 

Without  a  knowledge  of  Physical  Geography  we  look 
upon  the  earth  and  its  diverse  agencies,  as  the  young  appren- 
tice maybe  supposed,  when  he  lirstenters  the  machine-shop, 
to  look  at  the  various  parts  of  the  steam  engine  which  he 
sees  there  lying  about,  but  ready  to  be  put  together.  There 
they  are,  all  the  different  parts,  fly-wheel  and  crank,  piston, 
valve  and  ratchet,  steam-chest  and  boiler.  Though  they 
have  so  little  resemblance  to  each  other,  and  look  so  little 
like  a  compact  and  powerful  machine,  yet,  when  he  comes 
to  see  them  put  together,  to  have  the  fires  lighted,  steam 
raised,  and  the  engine  started,  he  discovers  at  once  that 
each  part  is  made  to  fit  into  another  and  work  with  its  fel- 
low; that  the  whole  is  according  to  dengii,  and  that  every 
piece  has  a  special  office  to  fulfil,  failing  in  which  the  whole 
machine  would  be  thrown  into  confusion.  So  it  is,  as  the 
study  of  our  science  will  show,  with  the  terrestrial  machin- 
ery. 

2.  Bistribiitioii  of  Laud.—Oi  the  197,- 
000,000  of  square  miles  which  embrace  the  surface 
of  the  earth,  about  144,000,000  are  covered  by 
water,  and  53,000,000  by  land.  In  other  words, 
there  is  nearly  three  times  a.s  much  water  as  land. 

The  land  is  found  in  nia.sses  of  irregular  shape 
and  size,  Mhich  are  separated  by  intei-vening  por- 
tions of  water.  The  six  largest  land-masses  are 
called  Continents.  The  smaller  divisions  of  land 
are  called  Islands. 

Most  of  the  land  is  in  the  northern  half  of  the 
globe.  It  surrounds  the  North  Pole  in  an  almost 
continuous  ring,  and  from  the  polar  regions  it  ex- 
tends in  long  irregular  masses  towards  the  south. 
We  may  consider  these  masses  as  forming  three 
pairs  of  continents.  The  division  comprising 
North  America  and  South  America  affords  the 
most  perfect  example  of  this  arrangement;  that 
consisting  of  Europe  and  Africa  is  less  well  de- 


fined ;  while  that  is  most  irregular  which  com- 
prises Asia  and  Australia. 

In  regard  to  shape  the  continents  follow  a  gen- 
eral law.  They  spread  out  broadly  towards  the 
north,  while  towards  the  south  they  taper  to 
points,  or  throw  out  peninsulas.  Tiius,  in  general, 
they  approach  the  form  of  a  triangle.  This  is 
strikingly  illustrated  in  the  case  of  Africa  and  the 
two  Americas.  Europe  and  Asia  combined  form 
a  vast  triangle.  Australia  is  the  only  marked  ex- 
cejition  to  the  rule. 

Almost  all  the  large  peninsulas  are  southern 
projections  from  the  continents. 

3.  Northern  and  Southern  Hemi- 
HpJteres, — The  globe  is  divided  by  the  Equator 
into  a  Northern  and  Southern  Hemisphere. 
North  America,  Europe,  and  Asia,  two-thirds  of 
Africa,  and  a  portion  of  South  America  are  con- 
tained in  the  Northern  ;  Australia,  part  of  Africa 
and  the  greater  part  of  South  America,  in  the 
Southern.  There  is  three  times  as  much  land  in 
the  Northern  as  in  the  Southern  Hemisphere. 

The  Northern  Hemisphere  is  the  seat  of  knowl- 
edge, civilization  and  power.  It  is  the  commer- 
cial hemisphere. 

The  Southern  Hemisjjhere  has  never  been  the 
seat  of  power.  The  Peruvians  and  the  Javanese 
were  the  only  nations  which  attained  a  high  degree 
of  civilization  there.  Only  about  one-fifteenth  of 
the  population  of  the  globe  have  their  home  with- 
in this  hemisphere. 

4.  Land  and  Water  Hemispheres.-- 

The  earth  may  be  divided  into  two  hemispheres, 
one  of  which  contains  nearly  all  the  land,  and  the 
other  nearly  all  the  water.  These  hemispheres  are 
known  as  the  Land  Hemisphere  and  the  Water 
Hemisphere.  London  is  nearly  at  the  centre  of 
the  Land  Hemisphere  ;  New  Zealand  nearly  at  that 
of  the  Water  Hemisphere.  Australia  presents  the 
largest  extent  of  land  in  the  Water  Hemisphere. 

TOPICAL  .\:nalysis. 

I.    AEUANOEMENT  OP  LAND  MASSES. 

1.    Belation  of  land,  water  and  air. 
Design  in  crccition. 


FORMS    OF  LAND. 


27 


S.    Distribution  of  land. 

Extent  of  l.ind  and  wiitcr.  Conliiiuut«.  Islandn. 
Location  and  arr.ingcracnt  of  the  land.  General 
form  of  the  conlnionts. 

3.  northern  and  Southern  Hemispheres. 

Dividing  liiii!.  fonlinfUU  in  each.  I'roportlou  of 
land  and  population  in  Uie  two  hemispheres.  Of 
civilization   and  power 

4.  Land  and  Water  Hemispheres. 


Questions  on  Map  of  tub  World. — How  do  Europe  and 
Asia  compare  in  general  direction  with  North  and  South 
America  f  Which  o£  tlie  Old  World  continents  resembles 
the  New  in  general  direction  ?  What  zones  are  traversed 
wholly  or  in  part  by  each  of  the  continents  ?  What  is  the 
general  direction  of  the  mountain  ranges  of  the  Eastern 
Hemisphere  ?  Of  those  of  the  Western  ?  What  islands  are 
near  the  centre  of  the  larul  hemisphere  ?  What  islands  are 
near  the  centre  of  the  water  hemisphere  ? 


ir.     FORMS  OF  LAND. 

1.  Horizontal  Forms. — In  horizontal  form 
'the  various  land-masses  are  very  irregular.  Every- 
where the  sea  more  or  less  deeply  indents  the  shore. 
The  indentations  form  navigable  seas  or  sounds, 
harbors  or  roadsteads.  The  length  and  indenta- 
tion of  the  shore  line,  therefore,  are  indications  of 
the  commercial  capabilities  of  a  continent. 

Comparing  the  several  continents,  we  find  that 
the  southern  have  far  more  regular  outlines  than 
the  northern.  Their  indentation  is  comparatively 
limited,  and  their  coast-line  short.  The  contrast 
is  most  marked  between  Europe  and  Africa. 

EurojiB  has  six  times  more  coasl-line  i/i  projjor- 
tion  lo  its  area  than  Africa.  The  effect  of  this 
has  been  very  important  in  the  history  of  the  two 
continents.  By  the  multitudinous  seas,  bays,  and 
gulfs  of  Europe  inter-communication  of  one  part 
of  the  continent  with  another,  and  with  other  por- 
tions of  the  world,  has  been  facilitated,  and  thus 
its  several  countries  have  been  rendered  accessible 
to  commerce  and  civilization.  Europe  has  enjoyed 
among  the  continents  the  leadership  in  commerce. 

Africa,  on  the  other  liand,  with  its  comparatively 
unbroken  coast-line  and  scanty  harbors,  has  been 
barred  by  nature  from  extensive  intercourse  with 
the  outside  world. 

North  America,  though  in  a  less  degree  than 
Europe,  is  pre-eminent  for  the  indentation  of  its 
sea-coast.  This  contributes  to  render  it  the  com- 
panion of  Europe  in  commerce  and  civilization. 

2.  Vertical  Forms. — By  vertical  forms  we 
mean  the  elevations  of  the  land  above  the  sea-level. 
With  very  insignificant  exceptions  all  the  land  is 
more  or  less  raised  above  the  water. 


The  Average  Elevation  of  the  earth's  surface 
is  not  great.  It  has  been  estimated  that  if  all  the 
mountains  were  levelled,  and  all  tlie  valleys  tilled 
up,  the  land  of  the  globe,  taken  as  a  whole,  would 
not  be  raised,  on  an  average,  as  much  as  1,000 
feet  above  the  sea. 

Although  the  mountains  are  so  massive  In  size,  and  roach 
so  far  into  the  blue  ether  that  their  highest  peaks  can  never 
be  scaled  ;  yet,  when  compared  with  the  size  of  the  earth, 
their  huge  proportions  dwindle  into  insignificance. 

A  mountain  five  miles  high,  which  is  higher  than  any  but 
the  loftiest  peaks  of  the  Himalaya  or  Karakorum,  rises 
above  the  sea-level  but  g^;,  part  of  the;  earth's  radius.  Hence 
upon  a  globe  sixteen  inches  in  diameter,  it  would  be  repre- 
sented by  an  elevation  of  only  t,',,,  of  an  inch,  about  the 
thickness  of  two  leaves  of  this  book. 

On  a  globe  sixteen  feet  in  diameter,  the  highest  mountains 
would  rise  above  the  surface  less  than  the  eiglith  of  an  inch. 

3.  Forms  of  Relief. — According  to  their 
relief,  the  various  forms  of  land  are  classified  as 
lowlands  or  highlands. 

Lowlands  arc  elevated  less  than  1,000  feet  above 
the  sea.     They  are  commonly  called  plains. 

Highlands  liavc  an  elevation  of  1,000  feet  or 
more  above  the  sea.  They  arc  called  plateaus  or 
table-lands  and  mountains.  There  is  no  uniform- 
ity in  the  use  of  the  term  hill.  It  commonly  des- 
ignates an  elevation  of  less  than  2,000  feet. 

4.  Plains  are  those  portions  of  the  earth's 
surface  which  are  level,  or  which,  though  diversi- 
fied with  hills,  have  only  a  moderate  elevation 
above  the  sea-level.  About  half  the  extent  of  the 
continental  surfaces  consists  of  plains.  If  covered 
with  grass,  but  generally  destitute  of  ti'ecs,  they  are 
called  jur«iV«e.s  in  our  country,  pamjxis  or  llanos  in 
South  America,  and  sfejipcs  in  Asia.  The  densely 
wooded  plains  of  the  Amazon  are  called  selvas. 

Plains  are  classified  according  to  their  origin  as 
marine  or  alluvial. 

Makine  Plain.s  arc  considered  to  have  been, 
at  some  remote  period  in  the  liistory  of  the  globe, 
portions  of  the  floor  of  the  sea.  Upon  them  are 
fotmtl  sometimes  saline  deposits,  sometimes  the 
remains  of  animals  and  jilants  that  must  have 
lived  in  salt  water.  Our  own  Atlantic  seaboard 
and  the  Caspian  region  in  Asia  are  noted  examples 
of  marine  plains. 

Alluvial  Plains  are  those  which  have  been 
formed  from  materials  washed  down  from  the  hills 
and  mountains  by  the  rain  and  the  rivers.  The 
Delta*  and  valley  of  the  Nile,  the  Delta  of  the 


*  The  term  Delta  was  originally  applied  to  the  deposit  formed  at  the 
mouth  of  the  Nile,  and  enclosed  by  its  two  main  outlets.  The  area  thus 
formed  was  triangular  like  the  Greek  letter  a  ii/elfa),  and  hence  the 
word  lias  been  applied  in  a  general  sense  to  alluvial  lands  at  the  mouths 
of  rivers. 


28 


FORMS  OF  LAND. 


Mississippi,  the  plains  of  the  Indus  and  the  Gan- 
ges, and  the  Black  Lands  of  Russia  are  alluvial. 
Such  plains  are  among  the  most  productive  por- 
tions of  the  surface  of  the  earth. 

The  Nile  Valley  and  that  of  the  Menam  in  Siam  are  an- 
nually overflowed,  and  covered,  when  the  flood  subsides,  with 
a  fine  sedimentary  deposit.  Tliis  consists  of  rich  fertilizing 
materials  brought  down  from  distant  mountain  slopes.  It 
imparts  perennial  fertility.  It  has  clothed  the  land  of  Egypt 
with  verdure  since  the  days  of  the  Pharaohs,  3,000  years 
ago.     It  secures  the  great  rice-crop  of  Siam. 

Plains,  centres  of  civilization. — Owing  to  their 
fertility  and  ease  of  cultivation,  i)lains  have  been, 
throughout  the  history  of  man,  centres  of  popula- 
tion, civilization,  and  power.  Tlie  imperial  glory 
of  Nineveh  and  Babylon,  the  culture  of  ancient 
Egypt,  the  enduring  prosperity  of  Cliina,  and  tlie 
unrivalled  wealth  of  India,  all  owe  their  origin  to  the 
treasures  brought  down  from  the  everlasting  hills. 

5.  TlateauH  or  Tahle-Iantlfi  are  broad 
elevated  areas  wliich  rise  above  the  level  of  the 
surrounding  surface.  The  name  suggests  that 
they  are  flat.  And  some,  indeed,  as  the  Llano 
Estacado  of  Texas,  are  as  level  as  the  prairies. 
Generally,  however,  they  present  a  surface  highly 
diversified.  Great  mountains  are  often  piled  up 
ujwn  them. 

Tlie  plateau  of  Thibet  consists  of  grassy  plains 
and  wide  basins,  often  containing  large  lakes,  en- 
girdled by  ranges  of  gigantic  snow-clad  mountains. 

The  aspect  presented  also  by  the  great  plateau 
lying  between  the  Rocky  Mountains  and  the  Si- 
erra Nevada  in  our  own  country,  is  that  of  a  vast 
uplifted  mass  from  which  tlie  mountains  rise ; 
while  the  plateau  of  Titicaca,  in  South  America, 
with  the  towering  peaks  of  the  Andes  embosoming 
its  upland  lake,  singularly  resembles  the  plateau 
of  Thibet. 

Iti  elevation  plateaus  vary  greatly.  Low  pla- 
teaus, like  the  desert  of  Sahara,  are  from  1,000  to 
3,000  feet  in  height.  The  loftiest  in  the  world  are 
those  of  Thibet,  10,000  to  15,000  feet  high,  and 
Titicaca,  about  12,000. 

Plaleaiis  unproductive. — The  plateau  regions  of 
the  world  are  for  the  most  part  unproductive. 
Many  of  them  are  absolute  deserts.  Hence  few 
plateaus  have  ever  become  centres  of  popula- 
tion and  ])Ower.  It  is  interesting,  however,  to  ob- 
serve that  the  table-lands  of  Mexico,  Peru,  Titicaca 
and  Thibet  have  each  been  the  seat  of  a  civiliza- 
tion peculiarly  its  own. 

The  desert  plateaus  have  undoubtedly  their  part,  to  per- 
form in  the  economy  of  nature.  They  are  not  wastes  in  the 
sense  of  being  wasted  or  useless  areas.  Their  effect  upon 
the  rainfall  and  its  distribution  is  most  imi^ortant.  It  will 
be  more  fully  considered  when  we  treat  of  the  moisture  of 
the  air.     [See  p.  89.] 


6.  Mountains  are  elevations  rising  above  the 
general  level  of  the  land  to  the  height  of  2,000 
feet  or  more.  Sometimes  they  stand  singly,  like 
Etna  or  Vesuvius,  but  are  generally  joined  one  to 
another  and  form  a  connected  series.  Such  a  series 
is  called  a  mountain  chain,  or  range.  The  top  of 
the  chain  is  called  the  crest. 

Mountain  chains  are  seldom  solitary.  Usually 
two  or  more  are  parallel,  or  nearly  parallel,  with 
one  another,  forming  what  is  called  a  mountain 
system.  The  Andes,  the  Alps,  and  the  Appa- 
lachians are  examples.  In  all  of  these  there  is 
not  simply  one  long  line  of  mountains,  but  a  num- 
ber of  associated  and  nearly  parallel  ranges. 

The  Formation  of  Mountains  is  a  subject 
which  properly  belongs  to  geology.  It  is  gener- 
ally considered  that  mountains  liave  been  formed 
mainly  by  two  jirocesses  :  (1)  what  is  commonly 
called  the  crumpling  of  the  surface  of  the  earth  ; 
(2)  the  action  of  volcanic  vents.  The  latter  of 
these  has  already  been  sufficiently  discussed  in 
treating  of  the  formation  of  volcanic  cones.  [See  p. 
15.]  The  former  requires  some  explanation,  since 
the  great  mountain  systems  of  the  world  are 
thought  to  be  due  to  it. 

The  crumpling  ov  folding  process. — Suppose  the 
earth  to  have  been  at  some  period  of  its  long  past 
history  a  heated  mass.  The  heat  subsides.  The 
outside,  of  course,  cools  before  the  interior,  and 
becomes  a  spherical  crust,  while  the  parts  under- 
neath are  still  heated  and  form  a  pasty  sphere. 
This  in  its  turn  cools.  In  doing  so  it  contracts. 
What  is  the  consequence  ?  Some  portions  of  the 
solid  crust  fall  in  toward  the  centre  of  the  earth. 


STUAT.\   FULUED. 


In  this  process  the  crust  must  obviously  be  crum- 
pled or  folded  somewhat  like  the  skin  of  a  baked 
apple,  so  as  to  be  packed  into  the  diminished  space. 
The  diagram  will  perhaps  serve  to  convey  an  idea 
of  this. 

Two  cases  may  occur  :  (lUf  the  strata,  when  depressed, 
are  in  a  plastic  state,  there  will  be  a  simple/f xwre  or  curv- 
ing at  the  points,  n  a ;  (3)  if  the  strata  are  quite  cooled,  then 
there  may  arise  a  fracture  at  the  same  points.  The  former 
ease  may  be  compared  to  the  bending  of  a  piece  of  whale- 
bone or  a  steel  spring,  the  latter  to  the  bending  of  a  piece 
of  wood  or  iron.  It  is  obvious  that  the  one  process  will  give 
rounded  tops  to  the  mountains,  the  other  will  give  them 
jagged  peaks  and  sharp  ridges. 


FORxMS  OF  LAND. 


29 


7.  Vftllrt/s  are  depressions  through  which  usu- 
ally water-courses  run.  Every  mountain  range  is 
intersected  by  valleys,  and  every  mountain-system 
has  valleys  sej)arating  its  parallel  ranges.  Tlie 
valleys  intersecting  ranges  arc  called  transverse. 
Those  lying  between  parallel  ranges,  and  having 
therefore  the  same  general  direction,  are  called 
longlfudiiiah 

Tlie  fiirmation  of  mountain  valleys  is  due  to  tlie 
upheavals  and  depressions  which  have  disturbed 
the  surface  of  the  earth  in  the  manner  indicated  in 
paragra])]i  6,  jjrevious  page.  Tlie  formation  of  val- 
leys is  really  a  part  of  the  folding  process  by  which 
mountains  are  formed.  The  action  of  running 
water  has,  of  course,  widened  and  deepened  them. 


LORADO   RIVER. 


Valleys  traversing  plains  and  plateaus  have  been 
formed  by  the  erosive  action  of  water.  Of  such 
valleys  the  most  extraordinary  in  the  world  are 
the  cafions  of  our  western  rivers. 

That  of  the  Colorado  is  a  gorge  shut  in  by  almost  perpen- 
dicular walls  of  rock.  It  is  from  3,000  to  0,000  feet  in  depth, 
and  300  miles  long.  The  caiions  are  among  tlie  most  im- 
pressive e\'idences  of  the  age  of  our  earth.  Hundreds  of 
thousands  of  years  would  be  a  brief  period  for  performing 
the  work  of  wearing  away  the  solid  rock  by  running  water 
to  the  depth  of  more  than  a  mile. 


Transverse  valleys  render  it  possible  to  cross  the 
lofty  mountain  ranges.  Human  ingenuity  and  in- 
dustry have  improved  these  natural  courses  of 
travel,  or /lasses,  as  they  are  called,  and  some  of 
them  liave  l)ecn  made;  marvels  of  engineering  skill. 
The  Simphin,  St.  Bernard,  and  the  St.  Gothard, 
crossing  the  Alps,  are  among  the  most  noted.  The 
Al])ine  tunnels  have,  to  a  large  extent,  taken  tlie 
place  of  the  passes. 

8.  Causes   and   Effects    of   Relief. — 

Few  topics  connected  with  Physical  Geography 
have  greater  interest  than  tlie  questions,  how  were 
the  elevations  of  the  eartli  jiroduced,  and,  of  what 
use  are  they  in  the  terrestrial  machinery. 

Cal'ses. — What  precisely  may  have  been  the 
cau.sos  of  the  general  elevation  of  tlie  continents, 
we  cannot  with  certainty  tell.  On  the  principle 
that  like  effects  are  due  to  like  causes,  we  should 
conclude  that  similar  forces  produced  the  general 
elevation  as  those  to  whicli  we  refer  the  formation 
of  mountains.  Whatever  may  be  our  conclusion  on 
this  point,  it  is  clear  that  there  have  been  forces 
at  work  for  tmtold  ages,  silently  and  gently,  but 
steadily  raising  some  portions  of  the  earth's  sur- 
face, and  dejiressing  others. 

In  many  cases  it  is  evident  tliat  not  only  low- 
lands such  as  the  Mississij^pi  Valley,  but  even 
mountain  tops,  were  once  at  the  bottom  of  the  sea. 
Norwayand  Sweden,  with  the  Scandinavian  moun- 
tains, are  rising  at  the  rate  of  2i  to  5  feet  in  a  cen- 
tury. On  one  of  the  mountains  of  Wales  is  an 
ancient  sea-beach  elevated  1,300  feet  above  the 
present  shore. 

On  the  other  hand  many  parts  of  what  is  now 
the  ocean  floor  were  once  dry  land.  Greenland  is 
gradually  sinking. 

There  is  reason  to  believe  that  all  that  part  of 
the  Pacific  Ocean,  embracing  an  area  of  several 
millions  of  square  miles,  which  so  abounds  in  coral 
reefs,  is  gradually  subsiding. 

Effects. — The  elevations  of  the  earth's  surface, 
though  in  one  sense  insignificant,  are  properly  to 
be  regarded  as  important  regulators  of  climate. 
Not  many  hundred  feet  added  to  the  relief  of  a 
country  would  suffice  to  alter  its  physical  aspects 
entirely,  converting  vineyards  into  pasture  lands, 
or  pasture  lands  into  regions  of  perpetual  snow. 
Eeverse  changes  would  result  from  a  corresponding 
diminution  in  the  average  elevation.     [See  p.  7-L] 

Again:  Relief  is  the  great  regulator  of  drainage. 
If  the  surface  of  the  earth  had  been  a  dead  level, 
without  a  hill  to  embellish  the  landscape,  there 
would  have  been  no  water-courses.  The  whole  land 
would  have  been  one  broad  marsh  incapable  of 
drainage,  and  unsuited  for  human  occupation. 


r 


30 


RELIEF  FORMS  OF  THE  CONTINENTS. 


TOPICAL  ANALYSIS. 
II.    POUMS   OF   LAND. 

1.  Horizontal  Forms. 

Irregularity  nf  continental  oullinos.  Difference  be- 
tween northern  and  southern  continents.  Rela- 
tion of  this  difference  to  commerce. 

2.  Vertical  Forms. 

Average  elevation  of  the  Inml.  Relative  inyig- 
uificancc  of  the  higho^it  clevaiiuus. 

3.  Forms  of  Relief. 

Lowlands,     llighlimds. 

4.  Plains. 

Extent  and  varictiej-  of  plains.  Marine  Alluvial. 
Relation  of  plaina  to  civilization, 

6.    Plateaus. 

General  eliaractor.    Eluvation.     rroductivencss. 

6.  Mountains. 

Distribution,  formation.  Cruniplinjj  and  folding 
process. 

7.  Valleys. 

Transverse.  Longitudinal.  Formation  of  valleyp. 
Of  western  cai^ons.     Mountain  passes. 

8.  Causes  and  Effects  of  Belief. 

Tkpt  Qfestton?.— Can  yon  name  any  region  that  U  lower  than  the 
Fea-Ievel  ?  What  locality  contains  the  highest  mount^iins  in  the  world? 
Is  the  Mississippi  Valley  transverse  or  longitudinal  ?  The  valley  of  the 
Amazon  ?  Of  the  Potomac  ?    Relation  of  mountain  passes  to  commerce. 


III.     RELIEF  FORMS  OF  THE  CONTI- 
NENTS. 

1,  General  FeatiireH  of  f'ontineiital 
Relief. — There  arc  certain  features  of  relief  which 
belong  to  all  the  continents  in  gencrfil.  (1)  Each 
continent  is  bordered  by  mountains.  [2)  Each  con- 
tinent is  traversed  in  the  direction  of  its  gix'atest 
length  hy  a  grand  mountain-system.  The  line  of 
direction  taken  by  the  principal  mountain-system 
is  termed  the  main  or  primary  axis  of  elevation. 

This  axiul  line  is  not,  however,  in  any  case 
jilaced  centrally,  as  the  word  axis  might  seem  to 
imply,  but  far  to  one  side  of  the  continent.  It 
thus  divides  the  continent  into  two  unequal  slopes. 
(3)  For  the  most  part  a  subordinate  system  occurs 
in  each  of  the  continents.  This  system  follows  a 
secondary  axis  of  elevation.  (4)  The  central 
portions  of  each  continent  are  comjjaratively  de- 
pressed. 

Note. — The  relief  maps  and  profile  Bections  accompanying 
them  will  be  found  very  ueeful.  Their  examination  iu  connec- 
tion with  the  text  will  serve  to  imjiress  upon  the  minds  of  the 
pupils  the  conspicuous  features  of  continental  relief. 

The  heavy  black  lines  upon  the  maps  represent,  in  a  general 
way,  the  extent  and  direction  of  the  mountain  chains.  The  ele- 
vations and  depressions  are  shown  in  the  profile  sections.  They 
are  indicated  also  by  the  buff  and  green  colors  on  the  maps. 
The  buff,  according  to  the  depth  of  its  tint,  represents  elevations 
of  greater  or  less  altitude.    The  green  indicates  lowlands. 


North  America. 

1,  North  America  conforms  very 
closely  to  the  general  principles  of 
continental  relief.  It  has  a  pri- 
mary highland,  a  secondary  high- 
land, and  a  great  central  depres- 
sion. 

2.  PaeificHifjhIaua.—ThQ 

primary  elevation  of  North  Amer- 
ica is  the  vast  area  known  as  the 
Pacific  Highland.  It  consists,  in 
general,  of  a  high  plateau  from 
which  rise  the  Rocky  Mountains 
and  the  parallel  Sierra  Nevada  and 
Cascade  ranges.  The  plateau  varies 
in  breadth  from  300  to  600  miles. 
The  general  ele'vation  increases 
toward  the  south.  On  the  Arctic 
shores  it  is  800  feet  above  the  sea  ; 
in  Mexico  it  is  more  than  8,000. 

The  Rocky  Mountain  System 
is  composed  of  several  nearly  paral- 
lel ranges  which  form  the  main 
axis  of  the  continent.  It  embracea 
also  numerous  intersecting  cross 
ranges.     The  system  extends  from 


RELIEF  FORMS  OF  THE  CONTINENTS. 


31 


r15000 

Sierra  Nevada           RockyMts. 

-1 0000 

/      \Grt.Basi)i/    ^     ^^v,^^ 

Appalachian 

5000 

y  ^— ^      ^^ 

._^ Central 

the  Arctic  Ocean  to  the  Isthmus  of  Piinama,  the 
Sierra  Madre  range  of  Mexico  being  regarded  as 
the  southern  prolongation. 

From  the  plateau  upon  wliich  the  mountains 
stiuid  they  do  not  attain  a  height  of  more  than 
6,000  to  8,000  feet,  but  when  it  is  remembered 
that  the  plateau  itself  is  5,000  or  G,000  feet  high, 
it  will  be  seen  that  their  actual  elevation  above  the 
Bca-level  is  as  much  as  12,000  or  14,000  feet.  Their 
loftiest  peaks  are  about  15,000  feet  high. 

The  Sierra  Ne- 
vada AND  Cas- 
cade Mountains 
follow,  in  general, 
the  line  of  tlie  Pacific  coast.  They  form  the  west- 
ward wall  or  buttress  of  the  great  plateau.  In  alti- 
tude they  resemble  the  Eocky  Mountains.  Their 
loftiest  peak  is  Mount  St.  Elias,  17,500  feet  high. 

The  low  Coast  Range  stretches  along  the  shores  of  the 
Pacific  between  Cape  St.  Lucas  and  Vancouver's  Island. 

3.  The  Sscoiidary  Hif/hhmd  of  the  con- 
tinent comprises  the  Appalachian  mountain-system 
and  the  plateau  of  Labrador.  These  extend  from 
Labrador  nearly  to  the 
Gulf  of  Mexico.  The 
Appalachian  Moun- 
tains in  their  north- 
ern course  consist  of  a 
number  of  disconnect- 
ed groups.  To  the  southward  they  are  composed 
of  several  well  marked  and  nearly  parallel  ranges. 

The  general  elevation  is  not  more  than  about 
3,000  feet  above  the  sea,  but  the  loftiest  pe.aks  are 
nearly  7,000  feet. 

From  the  Appalachian  Mountains  the  land  de- 
scends gradually  to  a 
low,   narrow    coast 
plain    known    as  the 
"  tide  water"  region. 

4.  The  Central 
Ref/ion  between  the 
primary  and  second- 
ary highlands  is  called 
the  Great  Central 
Plain.  It  is  a  well 
marked  depression  ex- 
tending from  the  Arc- 
tic Ocean  to  the  Gulf 
of  Mexico. 

The  Height  of 
Land,  a  narrow  ridge 
crossing  it  from  east 

to  west,  having  an  elevation  of  from  1,000  to 
3,000   feet,  divides   it  into  two  distinct  i)ortions. 


SECTION   UF  NOUTU  AMERICA   FKOM   EAST   TO  WEST. 


One  slopes  to  the  north  and  drains  oil'  the  waters 
into  the  Arctic  Ocean  and  Hudson  Bay,  the  other 
inclines  toward  the  south,  and  drains  into  the  Gulf 
of  Mexico.  , 

South  America. 

1.  The  general  features  of  South  America 
are  similar  to  those  of  North  America.  Tiie  jiri- 
mary   elevation   of   the   continent   lies   along   its 

western  border. 
Secondary  high- 
lands are  found 
toward  the  eastern 
coast.  Central 
plains  lie  between  the  primary  and  secondary  high- 
lands. 

2.  The  Primary  Hif/hland  of  the  conti- 
nent is  formed  by  the  Andes,  the  grandest  mountain 
system  of  the  western  hemisphere.  It  stretches 
from  the  Isthmus  of  Panama  all  along  the  western 
edge  of  the  continent  down  to  Cajie  Horn,  a  dis- 
tance equal  to  one-sixth  the  circumference  of  the 
earth.     The  Eocky  Mountains  of  North  America 

may  be  appropriately 
regarded  as  its  north- 
ern prolongation. 


BRAZILIAN  HIGHLAND 


SECTION  OP  SOUTH   AMERICA   FROM   EAST  TO   WEST. 


The  Andes  are  re- 
markable for  the  con- 
tinuity of  their  height,  for  their  regularity  of  form, 
and  for  their  system  of  25arallel  chains.  In  the 
southern  portion  they  consist  of  a  single  chain  ; 
in  the  central  part  mainly  of  two  nearly  parallel 
chains  ;  and  in  the  north  of  three.  Eight  times 
these  parallel  chains  gather  into  mountain  knots, 


TOP  OF  THE  ANDES. 


and,  again  separating,  enclose  valleys  and  table- 
lands wonderful  in  height  and  extent. 


32 


RELIEF   FORMS    OF   THE    CONTINENTS. 


Of  these  table-lands  the  broadest  and  highest  is 
that  of  Bolivia. 

Passing  northward  we  observe  the  Jofty  crest  of 
this  imposing  system  crowned  with  hundreds  of 
snow-capped  peaks,  and  studded  witli  smoking  vol- 
canoes, all  the  way  from  the  Desert  of  Atacama  to 
the  centre  of  the  United  States  of  Colombia.  In 
the  whole  of  this  distance  of  nearly  three  thousand 
miles,  there  is  not  a  gap  or  a  pass  below  tlie  height 
of  11,500  feet.  Twenty  peaks  attain  a  height  of 
more  than  19,000  feet,  and  the  average  elevation 
is  estimated  by  Humboldt  at  11,840  feet. 

Very  imjiortant 
in  its  bearing  upon  rj 
the  physical  geog- 
rajihy  of  the  conti- 
nent is  the  singular 
proximity  of  the 
Andes  to  the  west- 
ern coast.  Their 
greatest  distance 
from  it  is  about  80 
miles. 


3.TheSecon<7- 
a  }'y  Hlf/hJands 

of  South  America 
are  those  of  Brazil 
and  Guiana. 

The  Brazilian 
Highland  is  a  broad 
plateau  region  trav- 
crsed  by  nearly 
parallel  ranges  of 
moderate  elevation. 
Their  loftiest  peaks 
are  from  5,000  to 
10,000  feet  high. 

The  Higlilandof 
Guiana  is  a  plateau 
supporting  several 
closely-set  ridges, 
the  most  important 
of  which  are  the 
Parime  Mountains. 
Maravaca,  the  culminating  peak,  is  nearly  10,000 
feet  high. 

4.  The  Central  Itegion  of  the  continent, 
like  that  of  North  America,  is  a  well-marked  de- 
pression lying  between  the  primary  and  secondary 
highlands.  It  is  called  the  Great  Central  Plain. 
It  consists  of  the  river-basins  of  the  Orinoco,  the 
Amazon,  and  the  La  Plata.  These  are  divided  by 
ridges  so  low  and  so  narrow  that  the  three  together 
may  not  unfairly  be  considered  as  forming  one 
great  basin. 


The  following  curious  facts  will  show  how  nearly  alike 
their  level  actually  is.  The  Cassiquiarc,  which  rises  between 
the  Amazon  and  the  Orinoco,  forks,  after  running  some  dis- 
tance, and  sends  off  one  branch  to  the  south  to  unite  with 
the  waters  of  the  Amazon,  the  otiier  to  unite  with  tlio>e  of 
tho  Orinoco  on  the  north;  it  thus  connects  these  two  river- 
basins  by  a  water-way  that  permits  the  Indians  to  pass  in 
their  canoes  from  either  of  the  two  great  rivers  into  the 
other. 

Furthermore,  in  tlie  Brazilian  province  of  MattoGrosso 
there  are  two  springs  side  by  side,  and  within  a  few  feet  of 
each  other.  Prom  one  (he  water  flows  into  the  Amazon, 
from  the  other  into  the  La  Plata  ;  and  so  close  are  the  nav- 
igable waters  of  these  rivers  to  each  other,  that,  with  a  sin- 
gle portage  of  a  few 
miles,  the  voyager,  as- 
cending the  La  Plata 
from  the  sea.  may  re- 
turn to  the  ocean  again, 
either  through  the 
Amazon  or  the  Orinoco. 


(^ 


Europe. 


shown  by  those  of  the  New 


1.  Europe,  like 
North  America  and 
South  America,  has 
its  primary  and 
secondary  high- 
lands and  its  low 
plain  ;  but  the  ar- 
rangement of  these 
features  is  different 
from  that  which 
jirevails  in  the  New 
World.  Two  ob- 
vious differences 
jiresent  themselves : 

(1)  the  main  axis  of 
elevation  extends 
cast  and  west,  not 
like  the  Andes  and 
Eocky  Mountains, 
north    and    south ; 

(2)  the  mountain 
chains  have  not  tne 
same  well-marked 
parallelism     as    is 

World. 


2.  The  Primary  HigJdand  of  Europe 
stretches  all  through  the  southern  portion  of  the 
continent,  from  the  Atlantic  to  the  Black  Sea,  and 
we  may  say,  regarding  the  Caucasus  as  its  eastern 
prolongation,  that  it  reaches  the  shores  of  the 
Caspian. 

Beginning  with  the  Pyrenees,  as  its  western  ter- 
mination, it  culminates  in  the  Alps.  Eastwiird  of 
the  Aljis  it  throws  out  two  important  branches,  the 
Carjmthians  to  the  north,  and  the  Balkans  to  the 


RELIEF  FORMS  OF  THE  CONTINENTS. 


33 


Alps 


south.  These,  with  the  Dinarie  Alps,  enclose  the 
basin  of  the  Danube.  Tn  addition  to  these  ranges 
the  Apennines  of  Italy  and  the  mountains  of  Greece 
are  included  as  parts  of  the  j)rimary  system. 

The  Alps  arc  the  most  celebrated  of  all  the 
mountain-systems  in  the  world.  Their  historic 
and  poetical  associations  ;  the  grandeur  and  beauty 
of  their  varied 
scenery ;  the 
number  and  ex- 
tent of  their 
glaciers,  and 
their  accessibil- 
ity to  travellers, 
invest  them  with  an  interest  unrivalled  by  the 
loftiest  summits  of  other  lauds. 

Occu^ning  a  central  position  between  France 
and  Germany  on  the  north,  and  Italy  on  the  south, 
they  can  be  reached  in  a  few  hours  from  any  of 
the  great  cities  of  Europe.  Ownng  to  their  varied 
attractions  they  are  visited  by  so  many  thousands 
annually,  that  they  have  been  called,  not  inappro- 
priately, "  the  play-ground  of  Europe." 


Plain 


SECTION  OF  EUKOI'E  FROM  NORTU  TO  SOUTU. 


-*    Jt 


O    C    IS 


Now  and  then  a  muttering  Jike  distant  thunder  may  be 
caught,  as  some  loosened  mass  of  snow  or  ice  falls  with 
a  crash  into  the  valleys  ;  or  the  wind  brings  up  from  IjcIow 
in  fitfid  gusts  the  murmur  of  the  streams  whicli  wander 
down  the  distant  valleys." 

The  highest  ])eaks  of  the  Alpine  system  are 
Mont  Blanc,  15,781  feet,  Monte  Rosa,  15,220  feet, 
and  the  Matterhorn,  11,780. 

The  Ali)s  are 
destitute  of  ac- 
tive volcanoes. 
The-/'yreMec.s 
present  a  much 
greater  uni- 
formity of  ar- 
rangement than  the  Aljis.  Their  average  height 
(8,000  feet)  is  not  greatly  inferior  to  that  of 
the  Alps  (8,000  to  9,000  feet)  ;  but  their  highest 
peak.  Mount  Maladetta,  11,1G7  feet,  is  far  below 
the  towering  masses  of  Mont  Blanc  and  ]Monte 
Rosa.  The  passes  of  the  Pyrenees,  however,  are 
higher  and  less  practicable  than  those  of  the  Alps. 
The  Caiyatl'ians  separate  the  plains  of  Hun- 
gary from  the  great  low   plain   of  the  continent. 

Their    greatest 


As  we  climh  iJie  Alps,  says  a  distinguished  scientific  writer, 
"peali  rises  behind  pealv,  crest  above  crest,  with  infinite 
variety  of  outline,  and  with  a  wild  grandeur  which  often 
suggests  the  tossing  and  foaming  breakers  of  a  stormy 
ocean.  Over  all  the  scene,  if  the  air  be  calm,  there  broods 
a  stillness  which  makes  the  majesty  of  the  mountains  yet 
more  impressive.  No  hum  of  bcc  or  twitter  of  bird  is  heard 
so  high.  No  brook  or  waterfall  exists  amid  those  snowy 
heights.  The  usual  sounds  of  the  lower  ground  have  ceased. 


elevation  is 
about  9,000 
feet. 

The  Caucasus 
range  stretches 
from  the  Sea  of 
Azov  to  the 
Caspian.  Two 
of  its  peaks. 
Mount  Elburz, 
18,572  feet,  and 
Kasbek,  16,545, 
surpass  in 
height  the  lof- 
tiest summits 
of  the  Alps. 

Peninsulas. 
— High  Europe 
throws  out  three 
mountainous 
projections  to- 
w'ards  the  south: 
the  Iberian  or 
Sjjanish  Penin- 
sula on  the  west,  the  Italian  in  the  centre,  and 
the  Grecian  on  the  east. 

The  Iberian  or  Spanish  Peninsula  is  a  great  plateau  sur- 
mounted by  several  parallel  ranges.  The  Pyrenees,  which 
are  the  principal  of  these,  form  the  di\-iding  line  between 
France  and  Spain. 

In  the  Italian  Penijisula  we  find  the  Apennines,  an  im- 
portant prolongation  of  the  Alpine  system.    These  arc  more 


34 


RELIEF  FORMS  OF  THE  CONTINENTS. 


famed  for  their  beauty  than  for  their  altitude.  The  volca- 
noes of  Vesuvius,  Etna,  and  tiie  Lijiari  Islands,  are  consid- 
ered as  belonging  to  this  cliain. 

The  Grecian  Penin.iula,\\kii  the  Italian,  boasts  of  no  very 
clevatx-'d  ranges.  Its  mountains  are  famed  less  for  their 
height  than  for  their  historic  and  poetic  associations.  They 
were  the  mythic  homes  of  the  gods  of  aneic.'nt  Greece.  Tlie 
tlirone  of  Jupiter  rested  on  Mount  Olympus.  The  Balkans 
are  the  most  imjiortant  lange.  They  have  an  average  ele- 
vation of  about  5,000  feet. 

^  .5.  The  Secondary  Highlauds  comprise 
the  ranges  of  Scandinavia  and  the  Ural  mountains, 
together  with  others  of  less  importance. 


CLlMBINa  THE  ALPS. 


The  Scandinavian  mountains  consist,  for  the 
most  part,  of  a  broad  elevated  region,  intersected 
by  deep    and    gloomy  valleys.     Some    of    these 


"fiords,"  as  they  arc  called,  are  thousands  of  feet 
in  depth,  and  penetrate  far  into  the  country.  One 
of  them  is  100  miles  in  length. 

The  Ural  mountains  form  a  natural  boundary 
between  Europe  and  Asia.  They  extend  south- 
ward, 1,200  miles,  from  the  Arctic  Ocean  nearly 
to  the  Caspian  Sea. 

4.  Loiv  Europe  consists  of  a  vast  plain  lying 
northeast  of  the  primary  liighland.  It  is  bordered 
on  the  northwest  by  the  mountains  of  Scandinavia, 
and  on  the  northeast  by  the  Ui'al  range.  It  ex- 
tends from  the  Arctic  Ocean  to  the  Black  Sea,  and 
westward  as  far  as  the  Bay  of  Biscay. 

The  Valdai  Hills,  near  the  centre  of  the  plain, 
mark  the  highest  point  of  a  swell  which  separates 
the  rivers  flowing  into  the  Baltic  and  White  Seas 
from  those  which  enter  the  Black  and  the  Caspian. 

^  A  ^ 

Asia. 

1.  Asia,  like  Europe,  may  be  divided  into  two 
grand  sections.  High  Asia  and  Low  Asia.  As  in 
the  case  of  Europe,  the  highlands  lie  to  the  south  ; 
the  great  low  region  to  the  north. 

2.  The  Primary  HiyJilaud  of  the  con- 
tinent consists  of  two  portions:  (1)  the  various 
mountain  chains  which  radiate  from  the  central 
elevated  region  knomi  as  the  Plateau  of  Pamir ; 
and  (2),  the  Plateau  of  Tliibet. 

The  Pamir  is  called  by  the  Asiatics  the  "roof 
of  the  world."  In  shape  it  may  be  regarded  as  an 
irregular  square.  From  three  of  its  corners  gi'cat 
chains  project.  The  southeast  corner  is  the  start- 
ing point  of  the  great  ridges  of  the  Himalaya,  the 
Karakorum,  and  Kuenlun.  From  tlie  northeast- 
ern comer  the  Thian  §han  range  takes  its  origin. 
From  the  southwestern  starts  the  line  of  the  Hin- 
doo Koosh. 

The  Plateau  of  TJiiiet  lies  between  the  Him- 
alayas on  the  south,  and  the  Kuenlun  mountains 
on  the  north.  It  is  the  loftiest  table-land  in  the 
world,  having  an  extreme  elevation  of  about  15,000 
feet. 

The  Himalayan  Range  stretches  eastward 
from  the  Pamir  in  an  unbroken  course,  for  a  dis- 
tance of  1,500  miles.  Its  breadth  varies  from 
150  to  350  miles,  and  its  mean  height  has  been 
estimated  at  6,000  feet  higher  than  that  of  the 
Andes.  Over  forty  of  its  peaks  rise  to  an  altitude 
of  23,000  feet,  and  more  than  120  reach  20,000 
feet.  Mount  Everest,  with  an  elevation  of  29,000 
feet,  is,  so  far  as  known,  the  highest  mountain  on 
the  globe. 

The  Himalayas  present  the  grandest  possible  moimtain 
scenery:  deep  gorges  wrapt  in  perpetual  twilight  gloom, 
frightful  precipices  ;  sombre  forests  of  rhododendrons  and 


RELIEF  FORMS  OF  THE  CONTINENTS. 


35 


pine  trees  ;  higher  up,  vast  glaciers  filling  the  ravines,  and 
ice  and  snow  covering  the  ridges  which  rise  one  above  an- 
other to  such  sublime  heights  as  must  ever  secure  tlieir  sum- 
mits immaculate  from  the  footsteps  of  man.  Everything  is 
colossal;  but  the  Himalayas  lack  the  smiling  valleys  and 
sheltered  lakes  which  impart  such  picturcsiiuc  charm  to  the 
Alj)s.  They  possess  the  grandeur  without  the  amenity,  the 
magnificence  with- 
out the  variety, 
which  mark  the  less 
elevated  European 
system. 

The  Passes  of  the 
Himalayas,  instead 
of  leading  through 

"low  gaps  and  over  gentle  declivities,  rise  up  into  the  regions 
of  perpetual  snow  and  ice,  and  are  so  difficult  as  to  be  of 
little  avail  for  the  purposes  of  commerce  between  the  people 
on  tlie  opposite  sides.  They  are  on  an  average  10,000  feet 
higher  than  those  of  the  Alps,  and  nearly  4,000  feet  higher 
than  those  of  the  Andes.  We  cannot  be  surprised  that  In- 
dia and  Siberia  are  practically  farther  removed  from  each 
other  than  if  they  were  separated  by  an  ocean,  nor  even  tliat 
the  o]ipo!>ite  slopes  of  the  Himalayas  are  occupied  by  men  of 
different  races. 

The  Karal-orum  range  travorsos  the  plateau  of 


The  Kuenlun  range  separates  Thibet  and  East- 
ern Turkestan,  and  is  prolonged  by  the  Chinese 
range  of  tlie  Peling  mountains.  Tiic  Thian  Shan 
range  form.s  the  northern  boundary  of  tlie  platean 
of  Eastern  Turkestan.  Some  of  its  peaks  attain 
the  height  of  20,000  feet. 


Siberian    Plain 


SECTION   OF  ASIA   FROM   NORTH   TO  SOUTH. 

The  Hindoo  Koosh  extends  in  broad,  massive 
ranges  westward  for  400  or  500  miles.  A  depression 
then  occurs.  The  range,  however,  is  really  con- 
tinued in  the  Elburz  mountain.?,  wliich  form  the 
northern  boundarj'  of  Persia. 

The  general  direction  of  the  great  mountain 
chains  of  the  primary  highland  region  is  east  and 
west. 

3.  The  Srroudary  Highlamls  comprise 

the  Altai  moun- 


Thibct,  and  is  believed  to  have  a  greater  average 
lieight  than  even  the  Himalayas.  It  contains 
Dapsang  mountain  (height,  28,300  feet),  believed 
to  be  the  liighcst  summit  next  to  Mount  Everest 
in  the  world. 


tains  and  their 
northern  con- 
tinuations, to- 
gether with  tho 
Great  Khingan 
range,  and  the 
ranges  of  south- 
eastern Asia, 
and,  finally,  the 
subordinate 
plateaus  of  the 
continent. 

The  Altai 
mountains  ex- 
tend in  a  north- 
easterly direc- 
tion, and  termi- 
nate inthe  Yab- 
jonoi  and  Stan- 
ovoi  ranges. 
They  separate 
the  desert 
wastes  of  Mon- 
golia from  the 
plains  of  Sibe- 
ria. Some  of 
their  peaks  are 
1 2,000  feethigh. 
The    Oriat    Kliingan    mountains,    with    their 

southern  ofEshoots,  form  the  eastern  barrier  of  the 

great  Desert  of  Gobi. 

Plateaus    are    a    prominent    feature  of    the 

Asiatic  continent.    A  series  of  them  extends  from 


36 


RELIEF  FORMS  OF  THE  CONTINENTS. 


the  shores  of  the  Eed  Sea  nearly  to  the  Pacific 
Ocean.  In  general  they  are  arid  and  rainless, 
sandy,  stony,  and  barren.  In  the  spring  the  sur- 
face is  thinly  sprinkled  here  and  there  with  grass 
and  herbs,  but  in  the  summer  and  autumn  it  is,  for 
the  most  part,  dry  and  slerile. 

The  sheltered  valleys  are,  however,  in  many  cases 
exceedingly  fertile.  In  such  valleys  there  is  a  set- 
tled population,  but  outside  of  them  the  jjlateau 
region  may  be  described  as  the  home  of  roving 
herdsmen  and  marauding  Bedouin. 

North  of  the  Kuenhin  mountains  are  two  plateaus,  Eastern 
Turkestan  and  the  Desert  of  Gobi.  These  arc  shut  in  on 
the  north  by  the  Thian  Shan  and  Altai  mountains.  The 
average  elevation  of  Eastern  Turkestan  is  about  2,000  feet 
above  the  sea-level ;  that  of  Gobi  about  4,000  feet.  Should 
we  enter  Gobi  from  Thibet,  we  should  make  a  descent  of 
nearly  9,0C0  feet. 

The  triangular  plateau  of  the  Deccan  in  India  rises  to 
the  average  height  of  about  3,000  feet.  The  sides  of  the 
triangle  are  the  Eastern  Ghauts,  the  Western  Ghauts,  and 
on  the  north  the  Vindhya  mountains. 

The  plateau  of  Iran  or  Persia,  including  large  portions  of 
Afghanistan  and  Beloochistan,  is  shut  in  by  the  Elburz 
and  Hindoo  Koosh  moiuitains  on  the  north,  by  the  Zagros 
chain  on  the  south,  and  the  Suleiman  on  the  east.  It  rises 
from  3,000  to  4,000  feet  above  the  sea-level. 

The  plateau  of  Armenia, with.  Ararat  (about  17,000  feet  liigh) 
for  its  culminating  point,  rises  to  the  westward  of  Persia. 

The  [ilateau  of  Asia  Jlinor  lies  westward  of  that  of  Ar- 
menia. It  has  an  average  elevation  of  2,500  feet.  The 
Taurus  ranges  bound  it  on  the  south. 


extends  through  Europe  and  Asia,  from  the  shores  of  llie 
North  Sea  to  Uehring  Strait,  a  distance  of  more  than  .5,000 
miles. 

The  Kirghiz  Stepjjes  are  wide  and  monotonous 
tracts,  covered  in  spring  with  rough  grass,  desert 
in  summer,  and  bleak  and  desolate  in  winter. 

The  Silerian  Flain  consists  of  prairies,  wood- 
lands and  tundras.  The  prairies  and  piny  forests 
are  in  the  southern  portions,  the  swampy  tundras 
on  the  northern  edges. 

Inferior  in  size  to  the  Siberian  Plain,  but  vastly 
more  imjjortant  for  their  influence  upon  the  his- 
tory of  the  human  race,  are  the  plains  of  China  and 
India.  They  snpjwrt  nearly  one-half  tlie  popula- 
tion of  the  globe. 

A  remarkable  depression  is  found  on  this  conti- 
nent. It  is  occupied  by  the  Dead  Sea,  the  surface 
of  which  is  1,300  feet  below  the  level  of  the  ocean. 


Africa. 


V^ 


1.  The  Continent  of  Africa  obeys  quite  close- 
ly the  general  law  of  continental  structure.  It  has 
mountain  ranges  along  the  coast,  while  a  plateau 
region  of  less  elevation  occupies  the  interior. 

2.  The   Primal'!/  Hif/hland  is  in  the 

east.  It  consists  of  an  elevated  region  which  ex- 
tends all  the  way  from  the  Isthmus  of  Suez  to  the 
Cape  of  Good  Hope.     One  important  portion  of  it, 


DESERT    OP    SAHARA. 


The  plateau  of  Arabia  forms  the  southwestern  projection 
of  the  continent. 

4.  The  Great  Loivland  of  the  Asiatic  con- 
tinent lies  to  the  north.  It  extends  from  the  shores 
of  the  Arctic  Ocean  southward  to  the  base  of  the 
Altai  mountains  and  the  adjacent  ranges,  and  com- 
prises the  Kirghiz  Steppes  and  the  Siberian  Plain. 

It  is  a  part  of  the  almost  continuous  depression  which 


the  plateau  of  Abyssinia,  attains  an  elevation  of 
7,000  to  8,000  feet.  The  culminating  jjoints, 
however,  are  the  snowy  heights  of  Kenia  and  Kili- 
ma-lSTjaro  (about  19,000  feet  high),  among  the 
Mountains  of  the  Moon.  South  of  these  elevations 
occur  the  Livingstone  mountains,  walling  in  lake 
Nyaesa  ;  and  nearly  at  the  southern  extremity  of 
the  continent  lie  the  Snow  mountains,  which  may 


RELIEF  FORMS  OF   THE  CONTINENTS. 


37 


be  considered  as  vast  terraces  ascending  from  the 
sea  toward  the  interior. 

3,  TIte  Secondary  Hiffh- 
hnuls  include  the  ranges  which 
border  tlie  northern  and  westei'n 
coasts.  The  Atlas  mountains  on 
the  north  consist  of  three  or  four 
parallel  ranges  which  ascend  from 
the  Mediterranean  stage  by  stage, 
and  increase  in  height  to  the 
westward. 

The  Kong  and  Cameroons 
mountains  are  the  principal 
ranges  on  the  west.  The  latter 
are  volcanic.  They  attain  at  some 
points  the  height  of  1-3,000  feet. 

4.  The  Inferior  of  the  con- 
tinent may  be  regarded  as  a  vast 
plateau  bordered  by  the  various 
coast  ranges.  Low  plains  are  to 
be  found  only  along  the  coast. 

The  plateau  region  may  be 
divided  into  two  sections  :  (1)  that 
portion  which  consists  of  prairies 
and  fertile  river  basins  ;  and  (3) 
the  arid  Sahara. 

The  Sahara  is  considered  to 
have  formed,  in  an  older  period  of  the  world's  his- 
tory, a  portion  of  the  bottom  of  the  sea.  It  is  not 
an  absolute  level.  Its  average  elevation  is  about 
1,200  feet,  but  it  contains  areas  which  are  4,000 
or   5,000   feet   in    height,    and    has   a   mountain 


which  are  below  the    sea-level.      They  are 
marshy  regions  known  as  the  chottes  (.s/iofs). 


the 


"'^::^ — r^ 


The  surface  of  the  desert  consists,  in  some  places, 
of  sharp  stones,  in  others  of  gravel,  in  others  again 
of  loose,  shifting  sand.  This  last  is  driven  before 
the  winds,  and  arranged  in  long  lines  like  billows  of 
the  sea. 

Australia. 


AUSTRALIA 


range  one  of  whose  peaks   is  nearly  8,000  feet 
high.     Southward  of  Tunis  are  found  depressions 


J.  Australia  resembles  Africa  in 
conforming  to  the  general  law  of 
continental  relief.  It  has  an  elevated 
border  and  a  depressed  interior. 

The  Primary  Highland  lies  along 
the  eastern  and  southeastern  shores. 
It  culminates  in  the  Australian  Alps, 
the  loftiest  peaks  of  which  are  about 
7,000  feet  high,  and  terminates  in 
York  Peninsula. 

The  Secondary  Highland,  border- 
ing the  western  and  northwestern 
edges  of  the  continent,  has  an  average 
elevation  of  2,000  to  3,000  feet. 

Of  the  Central  Lowland  only 
small  portions,  such  as  the  basins 
of  the  Darling  and  Murray  rivers, 
are  well  known.  Large  areas  are 
believed  to  be  desert.  A  character- 
istic feature  of  the  lowland  is  its  inland  salt  lakes, 
several  of  which  are  more  than  100  miles  in  length. 


38 


ISLANDS. 


TOPICAL  ANALYSIS. 
III.    BELIEI''   KORMS   OK   THE   CONTI.VENTS. 

General  Features  of  Continental  Relief. 

Looiliou  of  axial  line.    Central  depressions. 

North  America. 

1.  (lent rat  Features. 

2.  Pacific  IRglilaiul.  Description.  Rocky  mountain 
system.  Sierra  Nevada  and  Cascade  mountains. 
Coast  range. 

3.  The  Stscondaify  U'lijldand.  Description.  "Tide- 
water" region. 

4.  Central  Segioii.    Description.    Ueight  of  land. 

South  America. 

1.  General  Features. 

2.  Primary  tRghland.  Location.  The  Andes.  Re- 
markable features.    Elevation. 

3.  .Secotidanj  ITtghlands.  Brazilian  Highland.  Quiana 
Highland. 

4.  Central  Heg'mii.    Consists  of  what  f 

Europe. 

1.  General  Features,  as  compared  with  those  of  the 

American  continents. 
8.  Tlie  Primary  IRgMand.     Location.     Principal 

ranges.     The  Alps.    Circumstances  which  make 

them   celebrated.     The  Pyrenees.    Carpathians. 

Cimcasus    range.      Peninsulas  ;    Iberian,  Italian 

and  Grecian. 

3.  Secondary  Hlghtauds.  Scandinavian  mountains. 
Ural. 

4.  Low  Europe. 

Asia. 

1.  General  Features. 

a.  Tlie  Piimary  TRghland.  Divisions.  Plateau  of 
Thibet.  Himalayan  range.  Grandeur  of  its  scen- 
ery. Passes.  Karakorum.  Euenlun.  Thian 
Shan,  and  Hindoo  Koosh  ranges. 

3-  Secondary  J/lgfdaiids.  Consist  of  what  ?  Plateaus 
of  Asia,  extent  and  barrenness  of.  Eastern  Tur- 
kestan. Desert  of  Gobi.  Deccan.  Iran.  Armenia. 
Asia  Minor.  Arabia. 

4.  TTie  Great  Lowland.  Location.  Kirghiz  Steppes. 
The  Siberian  plain.  Plains  of  China  and  India. 
Dead  Sea  region. 

Africa. 

1.  Corre.y)ondence  to  the  general  law. 

2.  Primary  Ifighland.    Location.    Extent. 

3.  Secondary  Highlands,  include  what  ? 

4.  The  interior.     Divisions.    The  Sahara. 

Australia. 

1.  Conformity  to  the  general  law. 
Pri?nary  inghland. 
Secondary  Highland. 
Central  Lowland. 

Test  Questions. -Considering  Europe  and  Asia  as  one  continent, 
where  would  be  the  central  depression  ?  Do  you  know  anything  re- 
mnrkable  about  it  ? 


V 


IV.  ISLANDS. 


1.  Classificatiott.—A  portion  of  the  dry  land 
consists  of  islands.  These  are  divided  into  two 
general  classes,  continental  and  oceanic  islands. 


2.  Continental  Islands,  as  the  name  im- 
plies, are  situated  near  the  continents,  and  in 
earlier  periods  of  the  world's  history  many  of  tlicm 
doubtless  actually  formed  parts  of  the  continents. 
This  conclusion  is  based  upon  the  resemblances 
that  exist  between  the  islands  and  continents  in 
their  rocks  and  soils,  and  in  their  vegetable  and 
animal  productions. 

Prom  the  fact,  for  example,  that  in  past  geological  peri- 
ods the  same  animals  lived  in  Great  Britain  as  in  Europe, 
geologisis  are  convinced  that  Great  Britain  and  the  adja- 
cent islands  were  originally  connected  with  the  European 
continent. 

Continental  islands  are  usually  arranged  either 
in  a  line  parallel  to  the  coast  of  the  continent, 
or  upon  a  line  which  may  be  fairly  regarded  as  a 
continuation  of  the  continental  coast  line.  The 
Japanese  Islands  illustrate  well  the  parallel  ar- 
rangement ;  the  "West  Indies  and  Sunda  Islands 
are  arranged  upon  lines  which  may  properly  be  re- 
garded as  jirolongations  of  the  eastern  shores  of 
North  America  and  Asia  respectively.  [See  map, 
p.  24] 

3.  Oceanic  Jslands  are  situated  in  mid- 
ocean,  far  away  from  the  continents.  They  are 
arranged  sometimes  in  lines,  sometimes  in  groups 
of  irregular  shape.  They  are  strikingly  unlike  the 
continental  islands.  These  latter  are  made  up  of 
the  same  I'ocks  as  the  continents.  The  oceanic 
islands  are  not.  They  are  composed  either  of  vol- 
canic products  or  of  coral.  In  regard  to  forma- 
tion, oceanic  islands  are,  therefore,  of  two  kinds, 
volcanic  and  coral. 

4.  Volcanic  Islands  are  arranged,  as  a 
rule,  along  the  gi-eat  bands  or  belts  of  volcanic  ac- 
tivity which  traverse  the  globe. 

Most  of  them  are  found  within  the  volcanic 
belts  of  the  Pacific  and  the  Atlantic.  [See  jx  18.] 
There  are,  however,  exceptions  to  this  general  rule, 
many  volcanic  islands  being  situated  qtiitc  irregu- 
larly. It  is  curious  that  the  volcanoes  upon  islands 
in  the  Pacific  belt  are  among  the  most  active  in 
the  world  ;  those  in  the  Athmtic  belt  are  either  ex- 
tinct, or  are  bordering  on  extinction. 

Formation. — Volcanic  islands  are  formed  by 
the  accumulation  of  materials  thrown  out  by  sub- 
marine volcanoes.  Sometimes  such  islands  are 
formed  very  suddenly,  as  in  the  case  of  Graham 
Island,  in  1831,  and  of  one  off  the  Island  of  San- 
torini,  in  the  Mediterranean,  in  1866.    [See  p.  15.] 

In  elevation  above  the  sea-level,  volcanic  islands, 
owing  to  the  method  of  their  formation,  are  natu- 
rally far  higher  than  those  of  coral  origin.  Some, 
like  the  Sandwich  Islands,  attain  an  altitude  of 
many  thousand  feet. 


ISLANDS. 


39 


5.  Coral  Islands,  —  Multi- 
tudes of  islands  are  mainly  com- 
posed of  coral,  and  liencc  are  called 
coral  islands.  They  are  formed 
chiefly  by  the  agency  of  the  coral 
imJijp,  Ijiit  partly  by  the  action  of 
tiie  waves. 

The  Coral  Polyp. — The  polj^is 
themselves  must  first  be  described, 
before  we  can  rightly  appreciate 
tlieir  work.  There  are  many  differ- 
ent species,  but  we  need  to  concern 
ourselves  only  about  the  reef-build- 
ing polyps.  Of  these  there  are  va- 
rious kinds.  The  cut  represents  a 
piece  of  coral  crowned  with  a  colony 
of  tiny  laborers. 

Description. — The  numerous  rays  which 
project  from  the  polyps  are  called  tentacles. 
They  are  so  many  little  fans  which  the 
polyp  moves,  so  as  to  draw  a  current  of 
water  towards  his  mouth.  The  mouth  is 
represented  in  the  cut  by  a  slit  in  the  cen- 
tre of  the  rays.  The  body  of  each  polyp 
is  in  a  little  pocket,  or  hole,  in  the  sub- 
stance of  the  coral.  It  consists  of  an  outer 
sack  containing  an  inner  sack,  this  latter 
being  the  stomach.  In  the  open  space  be- 
tween these  two,  the  bony  part  of  the  skel- 
eton of  the  polyp  is  formed.  It  is  lime- 
stone, and  is  separated  by  the  polyp  from 
the  sea-water  which  is  continuously  sup- 
plied by  the  movements  of  the  tentacles. 

Then  again,  although  we  may  consider  each  polyp  as  an 
individual,  like  a  single  bee  or  ant,  it  is  to  be  observed  that 
the  members  of  such  a  colony  as  is  shown' in  the  cut  are 
not  altogether  independent.  A  common  fleshy  substance 
extends  from  one  to  the  other,  and  thisacts  as  the  individual 
polyps  do.  Like  them  it  separates  limestone  from  the  sea- 
water,  and  makes  out  of  it  a  sort  of  common  skeleton.  With 


i'uLYPs  EUXLUiNG  CORAL— {natural  size). 

endures  for  ages.  As  rapidly  as  individuals  die,  others  take 
their  place.  Young  polyps  actually  shoot  like  buds  out  of 
the  substance  of  the  older  ones,  and,  besides  this,  addi- 
tional multitudes  are  hatched  from  eggs.  One  vast  host  of 
workers  then  deposits  its  layer  of  limestone,  and  passes  out 
of  existence.  Another  and  another  succeeds,  and  thus  coral 
grows  and  rocky  columns  rise  through  the  waves  to  become 
the  supports  of  coral  islands. 


CORAL  REEFS  OFF  TUE  NORTH  FHORE  OF  TAHITI. 


this  the  skeletons  of  all  the  polyps  are  united  so  that  thoy 
form  one  dense  rock-like  mass.  This  substance  is  known  as 
coral. 

The  life  of  the  individual  poh^p  is  brief,  but  the  colony 


"Work  of  the  Polyp. — Let  \ts 
now  consider  what  we  may  term  the 
life-work  of  the  polyj).  It  consists 
in  the  building  of  reefs. 

Coral  reefs  may  be  classed  as  (1) 
fringing  reefs;  (2)  barrier  reefs; 
(.3)  atolls. 

Fringing  reefs  are  bands  of  coral 
rising  a  few  feet  above  the  water, 
and  surrounding  islands  or  .skirting 
the  shores  of  continents.     The  bil- 
lows dash  themselves  into  spray  on 
these  reefs,  but  leave  the  water  on 
the  inside  as  smooth  as  a  mill-pond. 
Barrier   reefs    are   the  same  as 
fringing  reefs,  only  that  they  are  further  removed 
from  the  land.    Some  of  them  are  only  a  few  miles 
in  circumference,  others  are  several  hundred. 


/ 


40 


ISLANDS. 


WHITSUNDAY     ISLAND. 


The  great  barrier  reef  of  Australia  is  1,200  mUes  long. 
The  island  of  New  Caledonia  and  many  others  are  protected 
from  the  sea  by  similar  reefs. 

An  atoll  is  a  reef  from  witliin  which  an  ishind, 
once  encircled,  has  disappeared.  It  consists,  there- 
fore, of  a  belt  or  strip  of  coral  enclosing  an  ex- 
panse of  water.  The  water  thus  enclosed  is  called 
a  lagoon. 

Atolls  are  usually  nearly  oval  or  circular,  but 
in  many  cases  they  are  quite  irregular  in  shape. 
Sometimes,  as  in  the  case  of  Wliitsunday  Island, 
they  are  complete  rings ;  but  most  frequently,  on 


liED    (JOKAL. 


the  side  not  exposed  to  the  prevailing  winds,  there 
are  one  or  more  breaks. 

The  atolls  are  almost  innumerable.  There  are  nearly  a 
hundred  of  them  in  the  Dangerous  Archipelago,  which  lies 
to  the  westward  of  Taliiti.  They  are  not  more  than  half  a 
mUe  across,  from  the  sea  to  the  lagoon.  In  their  highest 
parts  they  are  only  a  few  feet  above  the  water;  still  they  re- 
sist the  utmost  fury  of  the  waves.  They  are  thickly  covered 
with  vegetation. 


Work  of  the  Waves. — When  the  polj-ps  have 
reared  their  wondrous  structure  up  to  the  IcA'el  of 
low  water,  they  have  finished  their  part  in  the 
formation  of  the  coral  island.  Now  follows  the 
work  of  the  waves.  They  break  'oil  portions  of 
the  coral  growth.  The}^  next  sweep  these  portions 
into  a  ridge,  just  as  the  sand  is  swept  up  on  the 
sea-shore.  The  ridge,  heaped  up  by  successive 
additions  of  broken  coral,  finally  becomes  so  high 
that  it  overtops  the  waves,  and  an  island  is  formed. 

The  next  stage  is  the  appearance  of  vegetable  life. 
Floating  wood  lodges  among  the  coral  fragments. 
It  decays  and  forms  mould.  Seeds,  such  as  cocoa- 
nuts,  not  injured  b}'  salt  water,  are  wafted  to  the 
new-born  islet ;  others  may  be  carried  thither  by 
birds.  Under  the  stimulus  of  a  tropical  sun  they 
grow,  and  in  process  of  time  deck  the  dead  coral 
mass  with  living  green. 

The  bread-fruit  and  cocoa-palm  are  the  most 
important  of  the  forms  of  plant-life  that  flourish 
upon  the  coral  islands.  No  large  animals  live 
upon  them,  and  of  course  neither  metals  nor  coal 
are  found  on  them.  They  are  not  fitted  to  be  the 
abode  of  human  beings  at  all  advanced  in  the  scale 
of  civilization. 

G.  ''Coral  Groves"  and  Coral  Seas. — 

So  singularly  transparent  is  the  water  enclosed 
by  the  atolls,  that  the  ship,  as  she  lies  at  her  an- 
chor, appears  rather  to  be  suspended  over  the  bot- 
tom than  to  be  resting  on  the  deep.  I  have  seen 
plainly  coral-trees,  standing  in  groves  at  the  depth 
of  one  hundred  feet. 

The  coral  groves  of  the  ocean  floor  are  decorated  like  the 
gardens  of  the  land,  the  flower-like  polyps  answering  to  our 
pinks  and  daisies,  violets,  and  lilies.  Some  of  them  are  of 
the  brightest  and  softest  tints,  pink,  pearl  color,  and  bine, 
green,  purple  and  yellow.     They  strew  the  bottom,  which  is 


ISLANDS. 


41 


of  the  whitest  and  purest  sand;  or  Iiang  like  leaves  and 
flowers,  or  elingf  like  mosses  and  liebons  to  the  branching 
coral,  and  lend  rare  enchantment  to  the  scene.  Fishes  of 
many  colors,  with  exquisite  grace  of  movement,  dart  among 
the  branches.  They  are  as  multitudinous  as  bees  over  the 
flower-beds,  and,  with  their  polished  scales,  vie  in  brilliancy 
with  the  featheri'd  tribes  of  the  land.  To  look  down  upon 
such  a  scene  in  the  great  bosom  of  the  ocean  is  like  gazing 
U])on  t\w  splendors  of  fairyland  itself. 

The  full  beauty  of  the  coral  groves,  however,  cannot  be 
seen  from  above.  Their  admirer  must  dive  to  th(^  liottoin. 
Yet  not  without  risk  does  he  venture.  The  fire  coral  (Mil- 
lepora).  and  the  MeduScB  swimming  amid  the  treasures  of  the 
deep,  sting,  when  touched,  like  the  worst  of  nettles.  Black 
sea  urchins  drive  their  long  barbed  stings  into  the  flesh  of  the 
foot,  where  they  break  off  and  remain,  inflicting  painful  and 
dangerous  wounds.  But  the  worst  of  all  injuries  to  the  skin 
are  inflicted  by  the  coral  rocks  themselves,  owing  to  their 
myriads  of  hard  points  and  sharp  jagged  edges. 

7.  DistHbution  of  i'oriih — The  reef- 
building  polyps  are  confined  to  tropical  waters. 
The  central  part  of  the  Pacific  Ocean  is  the  scene 
of  their  greatest  activity.  They  are  also  found  in 
many  portions  of  the  Indian  Ocean,  in  the  Red 
Sea  and  the  Persian  Gulf. 

E.xcept  in  the  region  of  the  West  Indies,  at  the 
Bermudas,  and  off  the  coast  of  Brazil,  there  are  none 
in  the  Atlantic. 

The  area  within  which  tliey  are  at  vvorl;  is  not 
less  than  25  millions  of  square  miles. 

H.  Oi'igin  of  Atoll  a.— Many  of  the  reefs 
and  atolls  rise  from  very  great  depths  ;  but  the 
polyps  are  most  vigorous  in  water  not  deeper 
than  sixty  feet ;  and  in  water  that  is  more  than 
180  feet  deep  they  cease  to  live.  The  question, 
therefore,  arises,  how  can  the  foundations  have 
been  laid  for  certain  reefs  and  atolls,  which  are 
known  to  stand  in  water  not  less  than  a  mile  and 
a  half  deep  ? 

This  was  a  question  that  long  puzzled  Physical 
Geographers.  Finally,  Darwin  suggested  an  an- 
swer. It  enables  us  to  understand  not  alone  how 
atolls  in  deep  water  may  have  originated  ;  but 
also  how  atolls  in  general  were  formed.  It  is 
well  known  to  geologists  that  the  level  of  the 
ocean  bed  is  subject  to  change.  It  may  be  up- 
heaved, or,  again,  it  may  subside.  Darwin  con- 
jectured that  as  fast  as  the  coral  reef,  ages  ago, 
was  being  built  up  toward  the  surface,  it  was  car- 
ried down  by  the  subsidence  of  the  ocean  bed. 

ExPLANATioif. — Let  us  notice  the  successive 
steps  of  this  process.  There  is  reason  to  believe 
that  in  those  parts  of  the  ocean  where  atolls  now 
abound,  high  mountains  once  towered.  These 
mountains  were  islands.  The  polyps  built  encir- 
Dling  reefs  around  them. 

But  in  many  cases,  as   they  built  up,  a  gradual 


subsidence  took  place,  until  the  island  itself  disap- 
peared beneath  the  waves.  Tliis  subsidence  on  the 
one  hand,  and  this  I)uildiiig  up  on  the  other,  may 
have  continued  for  ages,  and  to  tlic  extent  of  thou- 
sands of  feet,  so  that  where  the  mountain  then 
was,  may  be  now  deep  waters  and  low  atolls.  Thus 


(L)  Section  ot  mouulain  rising  ahove  water.     (K  It)  Sections 
of  fringing  reef  resting  on  slopes.  .. 


(L)  Section  of  same  mountain  sulimergcd  :  (R  R)  Sections  of 
same  fringing  reef  become  an  atoll. 

the  mountain-top  was  replaced  by  the  lagoon,  and 
the  encircling  reef  became  the  atoll. 

Tahiti  affords  an  illustration  of  this  process.  It  is  a  vol- 
canic island  with  a  fringing  reef,  the  foundations  of  which 
rest  upon  the  submarine  slopes  of  the  island.  It  exhibits  the 
appearance  which  must  have  been  presented  by  existing 
atolls  before  the  subsidence  of  the  ocean  floor  had  carried 
down  beneath  the  surface  of  the  sea  the  mountainous  islands 
formerly  enclosed  by  them. 


TOPICAL    ANALYSIS. 


IV.    ISLAXDS. 


1.  Classification. 

2.  Continental  Islands. 

Situation,  fliLiracter. 

3.  Oceanic  Islands. 

How  distinguished  from  continental. 

4.  Volcanic  Islands. 

Location.     Formation.     Elevation. 

5.  Coral  Islands. 

How  fonncrt.  The  coral  polyp.  Dc-scription.  Work. 
Coral  reefs.  Kinds.  Alolls.  Work  uf  the  waves. 
Origin  of  vegetation.  Characteristic  animal  and 
vegetable  life.    Minerals. 

6.  Coral  Groves  and  Coral  Seas. 

Clearness  of.     Beauty  of. 

7.  Distribution  of  Coral. 

8.  Origin  of  Atolls.  ' 

Difficulty  connected  with.  Depth  at  which  the  coral 
polyp  can  work.  Darwin's  theory.  Illustration 
in  Tahiti. 

Test  Questions. — Would  you  consider  a  coral  island  a  desirable  place 
of  residence  ?    Why  ? 


42 


TOPICAL    ANALYSIS    FOR    REVIEW. 


TOPICAL   ANALYSIS   FOR  REVIEW. 


Arrangement  of  Land  Masses.     . 


Itelations  of  air,  wator  ami  land  to  cai-li  otlier. 

Extent  and  distribution  of  the  land  and  shape  of  the  continents. 

Northern  and  Southern  Hemispheres  compared  as  to  extent.     As  to  progress. 

Land  and  Water  Hemispheres. 


Forms  of  Land 


Horizontal   Forms. 


Vertical   Forms 


Lowlands.      Plains.      Various  kinds. 


[^    Highlands. 


f  Plateaus. 

Mountains.     Fonnation  of. 

Valleys.     Kinds.     How  formed. 
L  Causes  and  effects  of  relief. 


r  General  features  of  continental  relief. 
I    North  America. 

South   America.      Resemblance  to  North  America. 
Relief  Forms  of  the   Continents.  <    Europe,  general  description.      Alps.      Peninsulas  of  High  Euroije. 

Asia. 

Africa.      The  Sahara. 
^  Australia. 


f  ContinentaL 


Islands. 


f    Volcania 


Oceanic  . 


(^    Coral. 


C  Coral  Polyp. 

Coral  Reefs.     Classes  of. 

Development  of  the  reef  into  an  island. 
I    Distribution   of  Coral. 
'   Origin  of  Atolls. 


?^ 


PART       III. 


THE    WATEK. 


I.     PROPERTIES  OF  WATER. 

1.  Composition.— Tm-ning  from  the  liind 
we  come  now  to  the  consideration  of  the  water. 
Its  offices  are  of  tlie  highest  interest  and  impor- 
tance. 

Pure  water  is  composed  of  two  gases,  hydrogen 
and  o.xygen,  united  in  tlic  proportion  of  two  vol- 
umes of  hydrogen  to  one  of  oxygen. 

ii.  l*hifttical  I*)'ojte)'ties   of    loafer. — 

Tlie  properties   of   water   that   specially   interest 
the  Physical  Geographer  are  the  following  : 

(1)  water  changes  its  forms  with  remarkable 
readiness ; 

(2)  it  expands  when  passing  into  the  solid  state  ; 

(3)  it  has  extraordinary  capacity  for  heat ; 

(4)  it  lias  great  solvent  power. 

Forms  of  Wateu. — The  three  forms  of  water 
are  the  liquid,  solid,  and  gaseoTis.  Changes  of 
temperature  that  are  of  common  occurrence  cause 
it  to  pass  from  one  to  another  of  these. 

Now  it  becomes  a  solid.  Falling  gently  as  snow, 
it  muffles  up  the  young  plants  as  with  a  mantle, 
screening  them  from  the  biting  winds  of  winter  ; 
as  ice,  it  covers  the  sui-face  of  the  lakes  and  the 
rivers,  and  protects  the  denizens  of  the  water,  as 
snow  does  the  insects  and  tender  plants  of  the 
land. 

Now  it  becomes  a  gas,  and  carries  off  water  from 
the  sea  to  supply  the  springs  among  the  moun- 
tains that  give  drink  to  man  and  beast ;  or,  man- 
tling the  earth  with  an  invisible  screen,  prevents 
the  too  rapid  escape  of  its  warmth  at  one  time  ; 
or,  assuming  the  form  of  clouds  in  the  sky,  shields 
it  from  the  too  great  heat  of  the  sun  at  another. 

Having  fulflllcd  these  duties,  it  turns  again  into  beauti- 
ful, (lancing,  laughing  water.  Enduring  as  the  mountains, 
it  is  one  of  the  few  visible  things  on  earth  upon  which  time, 
since  the  world  began,  has  wrought  no  marring  change. 
Friction  abrades  it  not,  nor  have  all  the  keels  that  have 
ploughed  the  ocean  wasted  so  much  as  one  single  drop  of 
it.  There  it  is.  pure  and  bright,  just  as  it  came  from  the 
hands  of  its  Maker;  its  power  is  imimpaired  and  always 
fresh;  it  is  ever  busy  and  never  weary. 

E.\p.\.NSiON  OF  Watek. — Water  expands  when 


passing  from  the  liquid  state  to  the  solid.  This 
is  probably  due  to  the  fact  that  its  ])articles,  when 
crystallized,  require  more  space  than  l)efore.  When 
cooled,  it  follows  the  general  law,  and  contracts  un- 
til it  reaches  the  temi)erature  of  39J°  Fahr  Be- 
low this  it  disobeys  the  general  law,  and  expands 
till  it  reaches  32'  Fahr.,  its  freezing  point.  Then 
suddenly  it  hardens  into  ice,  and  attains  its  maxi- 
mum cx])imsion. 

Because  ice  is  more  exjjanded  than  water,  it  is 
lighter  titan  water,  and,  as  we  all  know,  it  floats. 
The  law  by  which  ice  floats  is  one  of  the  beautiful 
and  benign  jirovisions  of  nature.  Were  ice  heavier 
than  water,  it  would  sink  as  fast  as  it  was  formed, 
and  our  river-channels  and  shallow  lakes  would  be 
filled  with  solid  ice  from  the  bottom  to  the  top. 

Expansive  Force. —  Another    important    conse 
quence  of  the  expansion  of  water  lolien  freezing  is 
that  it  exerts  a  force  that  is  jjracticallg  irresistible. 
It  sunders  the  solid  rock   from  the  foundations  of 
the  mountains,  and  crumbles  it  into  fragments. 

One  of  the  most  interesting  effects  of  the  force  exerted 
by  freezing  water  occurred  in  Norway  in  1717.  The  snow 
covering  a  rocky  region  had  rapidly  thawed,  and  filled 
the  crevices  of  an  enormous  mass  of  rock  with  water. 
Suddenly  the  weather  changed.  The  water  enclosed  in  the 
crevices  of  the  rock  was  frozen.  Expansion  occurred,  and 
a  mass  of  rock  was  rent  away  and  precipitated  into  the 
neighboring  fiord.  The  waters  of  this  being  suddenly  driven 
from  their  channel  engulfed  a  household,  and  submerged  the 
adjoining  fields. 


KFFECTS   OP  KXl'ANSIUN    rKODUt  El)    BV   THE   FREEZING   OP  WATER. 

Two  bombs  having  been  filled  with  water,  and  the  fusee  holes  firmly 
closed  with  an  iron  stopper,  were  exposed  to  intense  cold  ;  on  freezing, 
the  stopper  of  one  was  projected  to  a  distance  of  more  than  150  yards, 
while  the  other  bomb  was  split  open  and  a  sheet  of  lee  was  forced 
through  the  crack. 


44 


PROPERTIES    OF   WATER. 


Capacity  for  Hf:at. —  Water,  of  all  hnoivn 
substances,  has  iJte  greatest  ccipacUy  fur  heat.  The 
heat  of  bodies  exists  in  two  forms  ;  as  sensible 
heat,  or  tliat  which  you  cau  feel,  and  insensible,  or 
tliat  which  you  cannot  feel.  The  latter  is  com- 
monly called  latent,  or  Iiidden  heat. 

In  the  process  of  evaporation  a  certain  quantity 
of  sensible  heat  is  absorbed  and  rendered  latent  ; 
in  the  op])osite  process  of  condensation  a  certain 
amount  of  latent  heat  is  released  and  made  sen- 
sible. 

'•  Ciapacityfor  heat"  means  the  power  possessed 
by  a  body  of  storing  away  heat,  and  rendering  it 
latent  or  unfelt. 

Explanation. — Suppose  you  take  a  cubic  foot  of  ice  at  27°, 
for  instance;  put  it  in  a  vessel  and  set  it  over  a  steady  lamp 
which  affords  sufficient  heat  to  raise  the  temperature  of  the 
ice  1°  a  minute.  At  the  end  of  five  minutes  the  ice  would 
be  at  32°.  The  heat  has  warmed  the  ice.  It  is  sensible, 
that  is,  you  can  feel  it.    The  ice  will  now  begin  to  melt,  but 


noticed,  how,  as  a  general  rule,  the  intense  cold  is 
mitigated  just  before  a  snow-storm.  This  is  due 
to  the  condensation  of  vapor  into  water,  and  the 
freezing  of  that  water  into  snow. 

It  has  been  computed  that  from  every  cubic  foot 
of  vapor  condensed,  and  frozen  into  snow,  heat 
enough  is  set  free  to  raise  more  than  100,000  cubic 
feet  of  air  from  the.  temjierature  of  melting  ice  to 
summer  heat. 

Nature  makes  great  use  of  these  counter-proper- 
ties, the  evaporation  and  condensation  of  water. 
She  bottles  away  the  heat  of  the  torrid  zone  in 
little  vesicles  of  vapor,  thus  cooling  the  atmos- 
phere. She  then  delivers  these  vesicles  to  the 
winds  to  be  by  them  transported  to  other  regions. 
There  they  are  condensed  into  rain,  and  their  heat 
set  free  to  warm  the  air  and  modify  the  climate. 
[See  p.  86.] 

The  Solvent  Power  of  water  is  another  prop- 
erty of  great  importance.  The  forms  of 
plant  and  animal  life  are  largely  built  up 
of  materials  which  enter  them  in  solution. 
Water  acts  as  a  vehicle  for  conveying  these 
materials  into  the  living  system.  It  is  es- 
sential therefore  to  the  maintenance  of  the 
life  of  the  world. 


CIRCDXATION    OF    W.\TER. 


the  heat,  instead  of  warming  the  ice  or  the  water,  only 
melts  the  ice.  At  the  end  of  143  minutes  all  the  ice  will  be 
melted;  but  the  temperature  of  the  water  will  still  be  32\ 
and  no  more.  Now  what  has  become  of  all  the  heat  received 
from  the  lamp  during  these  143  minutes?  It  has  gone  to 
convert  the  solid  into  a  fluid,  and  has  been  rendered  latent ; 
that  is,  it  has  been  stowed  away  and  concealed  in  the  water. 
Now  let  the  lamp  burn,  as  before,  with  sufficient  inten- 
sity to  raise  the  temperature  of  the  water  1"  a  minute.  In 
180  minutes  the  teinperature  will  be  raised  from  33°  to  312°, 
which  is  the  boiling-point;  and  the  water  will  feel  hot.  This 
again  is  sensible  heat.  The  boiling  water,  however,  now 
ceases  to  become  hotter,  but  if  you  let  it  stay  over  the  lamp, 
you  will  find  that,  at  the  end  of  967  minutes  more,  it  will 
have  boiled  away.  Now  the  vapor  thus  produced  has  iden- 
tically the  same  temperature  as  the  water,  viz.,  212°,  so  that 
967'  of  heat  will  have  been  rendered  latent. 

Evaporation  exerts  a  cooling  influence. — From 
the  above  it  is  evident  that  ice  or  water  becoming 
vapor,  absorbs  heat,  and  renders  it  "  latent "  or 
hidden. 

Condensation  of  water,  on  the  other  hand,  exerts 
a  warming  injltience.      You  must  have  frequently 


3.  Circulation    of    Water.— The 

readiness  with  which  water  changes  its  form 
and  i^asses  from  the  liquid  state  to  that  of 
vapor,  and  from  the  vajiorous  to  the  liquid 
state  again,  is  the  means  whereby  a  con- 
,^^^  stant  circulation  is  carried  on  from  the  sea 
to  the  land,  and  from  the  land  back  to  the 
sea  again. 

Let  us  trace  its  course.  Incessantly  the 
waters  of  the  sea  are  converted  by  the  sun's  heat 
into  invisible  vapor.  This  passes  into  the  air,  and 
the  winds  transjjort  it  to  the  land.  Condensed,  it 
falls  as  rain  or  snow.  It  fills  the  springs  and  replen- 
ishes the  I'ivers  ;  it  waters  the  thirsty  lands.  Por- 
tions of  it  find  their  way  back  to  their  home  in  the 
sea,  through  the  river  channels ;  others,  evapo- 
rated, rise  on  the  wings  of  the  wind,  and  again, 
being  cooled,  descend  as  rain  or  snow. 

And  thus  all  the  water  of  the  globe  comes  out  of 
the  sea,  as  from  a  reservoir,  and  it  all  finds  its 
way  back  there  again. 

TOPICAL     ANALYSIS. 
I.    PROPERTIES   OF    WATER. 

1.  Composition. 

2.  Physical  Properties. 

Forms  of  water.  Cause  of  changes  of  forms.  Uses 
ill  the  solid  form.  In  the  gaseous  form.  In- 
destructible nature  of  water. 


WATERS   OF   THE    LAND. 


45 


j  ExpanBion  in  freezing.    Important  result. 

Capacity  forlicat.     Ilcttt  rendered  latent  in  melting. 

In  evaporatidn. 
Effect  oCevaiJoratinn  and  condensation  of  water  on 

temperature  and  clinuite. 
Sol  vent  power. 

3.  Circulation  ofWater. 

The  great  reservoir. 

Test  Questions.— Name  some  forms  of  water  remarkal)Ie  for  tlieir 
beauty.  At  wliat  temperature  is  water  heaviest  ?  In  the  circulation 
of  water  between  land  and  sea  what  force  carries  the  water  down  to  the 
f^ea  ?    What  force  carries  it  back  to  the  land  ?  i 

r 

II.  WATERS  OF  THE  LAND. 

1.  Spriitf/s. — A  jjortion  of  the  rain  wliich 
falls  upon  the  land  flows  off  to  the  sea  through 
brooks  and  rivers.  The  larger  part  of  it,  however, 
does  not  flow  off,  but  accumulates  in  swamps  and 
lakes,  or  enters  the  ground.  The  latter  portion, 
sinking  into  the  earth  under  the  influence  of 
gravity,  finally  encounters  layers  of  rock  which  it 
cannot  penetrate.  It  then  follows  the  incline  of 
these  layers,  and  flows  for  a  greater  or  less  distance, 
until  it  reaches  a  point  where  the  land  is  depressed. 
Here  it  finds  egress  as  a  surface  spring.  If  the 
area  through  which  such  water  percolates  be  large, 
and  if  the  slope  along  which  it  flows  be  gentle, 
then  tlie  sjjring  will  be  perennial  or  unfailing. 

The  depth  to  which  percolating  water  descends  is  sur- 
prising. From  a  deep  well  sunk  in  a  certain  district  of 
Prance,  pieces  of  leaves  were  thrown  up  by  the  first  gush  of 
water  from  a  depth  of  about  400  feet.  These  leaves  were 
comparatively  fresli.  They  were  ascertained  to  have  come 
from  a  distance  of  about  150  miles  from  the  spring.  A 
similar  phenomenon  has  been  observed  in  other  places. 

Prom  the  percolation  of  water  through  the  earth  arises 
one  of  the  greatest  diificulties  in  mining  operations.  Before 
the  invention  of  steam-pumps  many  coal  pits  in  England 
had  to  be  abandoned  owing  to  the  fact  that,  in  the  expressive 
language  of  the  miners,  they  were  drowned. 


water,  they  crop  out  upon  the  surface.  Dipping  down, 
however,  they  arc  perhaps  1,000  feet  below  the  surface  at  the 
point  II.  Between  tliem  is  KK,  a  layer  of  gravel  through 
which  rain  water  can  percolate,  but  from  which  it  cannot 
escape,  being  contliied  by  AB  and  CD.  Trickling  down 
through  KK  the  water  accumulates.  The  tube  of  an  Arte- 
sian well,  I,  sunk  tlirough  AB,  enables  it  to  rise  to  the  height 
of  its  distant  source. 

When  the  source  of  supply  is  very  much  higher  than  the 
surface  where  the  well  is  sunk,  the  water  shoots  upward 
with  considerable  force.  The  jet  from  such  a  spring  near 
St.  Etienne,  in  France,  rises  to  a  height  of  about  25  feet. 

The  Frencli  colonists  in  Algeria  have  sunk  a  number  of 
Artesian  wells  on  the  margin  of  the  Great  Desert  of  Sahara, 
and  thus  supplied  themselves  with  an  abuntiance  of  water. 


INTEH.'IIIT  lENT    ^PltlNU. 


ARTESIAN    WELL. 


Action  of  ArtesianWells. — The  action  of  "  Artesian  wells," 
so  called  from  Artois  in  France,  where  they  were  first  used, 
very  clearly  illustrates  that  of  natural  springs. 

Let  US  suppose  that  AB  and  CD,  in  the  illustration,  are 
layers  of  rock  impervious  to  water,  and  that  at  a  dist;ance  of 
500  miles  or  more  from  a  desert  or  region  ill  supplied  with 


Intermittent  Springs. — The  springs  which 
have  excited  the  greatest  curiosity  are  those  which, 
from  their  alternate  subsidence  and  flow,  are  called 
intermittent.  The  cause  of  this  peculiarity  is 
illustrated  in  the  accompanying  cut,  and  will  be 
readily  understood  by  any  one  who  has  seen  a 
siphon  used. 

The  passage  from  the  reservoir  to  the  surface  of 
the  ground  is  curved  like  a  siphon  and  acts  in  the 
same  manner.  Water  percolates  through  the  fissures 
in  the  rock  and  accumulates  in  the  resei-voir.  As 
soon  as  it  rises  above  the  level  of  the  bend  of  the 
siphon,  h,  it  begins  to  flow,  and  does  not 
cease  till  it  has  fallen  below  the  mouth  of 
>-  the  passage  at  a.  Thus  the  reservoir  alter- 
nately fills  and  discharges  itself. 

Thermal  or  Hot  Springs  and  Geysers 
have  been  already  discussed.  [See  p.  14.  J 
It  remains  to  be  said  that  the  waters  of  such 
springs  may  be  ejected  in  two  ways  :  (1)  in 
~^  the  manner  above  indicated,  the  water  seek- 
T  ing  the  level  of  its  source;  or  (2)  by  the 
force  of  steam,  or  gases  superheated  by  the 
internal  heat  of  the  earth. 

Mineral  Springs  abound  in  many  parts  of  the 
world,  chiefly  in  mountainous  and  volcanic  regions. 
Their  waters  are  charged  with  variou.s  substances. 
Iron,  salt,  sulphur,  and  carbonic  acid  are  the  most 
common  ingredients. 


46 


WATERS    OF   THE    LAND. 


2.  Hivers. — Eivers  receive  their  sujiply  of 
water  from  si)rings,  or  molting  snow-fields  and 
glaciers.  From  various  springs  in  one  vicinity 
little  streamlets  pour  their  contril)utions.     Influ- 


WATEK    DOING    IT^     WullK  -  KA  \  IN  h;    UF    OCOBA.MBA, 

enced  by  gravity  these  seek  the  lowest  level.  They 
unite  and  form  a  river.  Again,  just  as  the  stream- 
lets issuing  from  a  number  of  springs  make  a 
river,  so  a  number  of  rivers,  all  seeking  the  chan- 
nel of  greatest  dejiression,  blend  together  and  make 
one  mighty  water-course.  Such  a  water-course,  with 
its  tributary  streams,  is  called  a  river-system. 

Not  unfrequently  on  the  way  to  the  sea  a  river  passes  by 
a  very  sudden  descent  from  a  higher  to  a  lower  level.  This 
gives  rise  to  cataracts.  According  to  the  violence  of  the 
descent  they  are  classed  as  rapids  or  waterfalts.  When  the 
descent  is  very  abrupt,  but  still  not  perpendicular,  the 
term  rapids  is  properly  employed.  The  cataracts  of  the 
Nile  and  the  rapids  of  the  St.  Lawrence  are  noted  illustra- 
tions. 

The  term  waterfall  is  used  when  the  water  drops  per- 
pendicularly.  The  loftiest  waterfalls  arc  those  of  the  Vosem- 
ite  in  California,  2,500  feet,  and  the  KeeLfoss  in  Xorway, 
2,000  feet  high. 

The  grandest  of  all  waterfalls  are  those  of  Niagara.    Here 


the  water  discharged  by  four  of  the  Great  Lakes  of  North 
America  plunges  in  a  single  leap  of  100  feet  from  the  terrace 
of  Lake  Erie  to  the  lower  level  of  Ontario. 

Offices  of  Rivers. — Rivers,  viewed  as  parts 
of  the  teiTcstrial  machinery,  have  two  main 
offices  :  (1)  they  bring  ahout  vast  changes  in  the 
surface  of  the  earth  ;  (2)  they  are  channels  ly 
which  the  drainage  of  the  land  is  accomplished. 

3.  H<nv  Rivers  Chanffe  the  Surface  of 
the  Eartli. — The  process  by  which  rivers  bring 
about  changes  in  the  surface  of  the  earth  has 
three  stages  :  erosion  ;  transjxjrtation  ;  deposit. 

Erosion  means  the  eating  away  of  the  solid 
materials  which  form  the  channel  of  a  river.  It 
is  brought  about :  (1),  by  the  solvent  power  of 
water  ;  and  (2),  by  its  mechanical  force  when  in 
motion.  These  two  combined  wear  away  the  more 
soluble  and  soft  clays  and  rocks  with  ease  ;  but  even 
the  hardest  cannot  witlistand  their  action. 

If  the  soluble  particles  of  a  rock  are  dissolved 
by  water,  the  surface  of  the  rock  becomes  disinte- 
grated, and  crumbles.  Xow,  when  a  stream  inces- 
santly runs  over  such  a  constantly  dissolving  and 
disintegrating  rock,  it  is  clear  that  erosion  will  make 
rapid  progress.     The  rock  will  be  worn  away. 

The  fragments  thus  removed  are  whirled  con- 
tinuously against  the  water,  against  one  another, 
and  against  the  sides  and  bottom  of  the  channel. 
And  thus,  as  the  river  rolls  on,  the  pai-ticles  eroded 
become  smaller  and  smaller.  In  the  upjier  course 
of  the  river  they  may  be  of  considerable  size.  In 
the  lower  course  they  are  reduced  to  fine  sand  and 
sediment. 

Example. — The  erosive  action  of  rivers  is  most  impres- 
sively illustrated  by  the  excavation  of  rocky  gorges.  That  of 
the  Niagara  and  the  canons  of  our  western  rivers  are  per- 
haps the  most  striking  examples  that  can  be  offered. 

The  Falls  of  Niagara,  it  is  evident,  were  at  one  period 
about  seven  miles  lower  down  the  stream  than  they  now  are. 
The  vast  volume  of  water  that  passes  over  the  falls  erodes 
the  edge  of  the  cliff  over  which  the  water  pours.  Falling 
from  the  height  of  about  ICO  feet  upon  the  rocks  below,  it 
wears  them  away,  and  thus  erosion  occurs  both  above  and 
below. 

It  has  been  computed  that  the  rate  at  which  the  falls  eat 
their  way  up  the  gorge  is  about  one  foot  a  year,  and  that 
therefore  it  has  taken  them  about  35,000  years  to  pass  back- 
ward from  Queenstown  to  their  present  point.  At  the  same 
rate  they  will  have  worked  their  way  back  to  Lake  Erie  in 
about  30,000  years  from  the  present  time. 

Tr.vxsportatiox. — The  finer  particles  of  eroded 
matter  are  carried  along  by  the  river  in  suspension, 
that  is,  simply  mixed  with  the  water.  The  coarser 
portions  are  rolled  onward  by  the  force  of  the 
current.  Tliis  twofold  action  constitutes  trans- 
jwrtafion. 

A  river  will  transport  eroded  matter  to  a  greatei 


/ 


WATERS    OF    THE    LAND. 


47 


or  less  distance,  and  in  greater  or  less  quantity,  in 
proportion  to  the  velocity  and  Yoliimc  of  its  cur- 
rent. AVater  moving  half  a  mile  an  hour  will 
carry  along  ordinary  taud.  If  tlie  velocity  bo  in- 
creased to  three-quarters  of  a  mile,  it  will  roll  fine 
gravel,  while  a  current  having  a  sjieed  of  three 
miles  an  hour,  can  sweep  along  ])ieces  of  stone  as 
large  as  eggs.  In  floods  masses  of  rock  as  large  as 
a  house  have  been  moved. 

As  to  the  quantity  of  matter  transported,  it  is 
estimated  tliat  of  visible  sediment  the  Klionc 
carries  into  the  Mediterranean  more  than  COO,- 
000,000  tons  annually,  and  of  salts  invisibly  dis- 
solved, more  tlian  8,000,000  tons.  Tlie  amount 
of  silt  carried  into  tlie  Gulf  of  Mexico  by  the 
Mississippi  in  one  year,  would  make  a  column  one 
mile  square  and  241  feet  high. 

Tlic  removal  of  this  matter  from  the  surface  of  the  valley 
reduces  its  average  level  one  foot  in  6,000  years.  Could  the 
same  rate  of  denudation  be  kept  up  continually  over  the 
entire  surface  of  North  America,  it  would  reduce  the  con- 
tinent, which  has  an  elevation  of  about  750  feet,  to  the  level 
of  the  sea  in  half  a  million  years. 

Deposit. — The  materials  borne  or  rolled  along 
by  rivers  are  deposited  at  various  points  in  the 
channel.  The  finer  portions  called  silt,  familiar 
to  us  as  muddy  slime,  are  carried  down  as  far  as 
the  mouth  of  the  river.  Farther  up  the  stream 
sandy  particles  come  to  rest ;  still  higher,  gravel 
is  deposited  ;  and  finally,  in  the  ujiper  course  of 
the  river  we  find  stones  of  greater  or  less  size. 

It  is  obvious  that  deposit  will  depend  very  largely 
u]ion  the  slope  of  the  river-bed  and  the  rapidity 

of  the  current.  Any- 
thing; that  checks  the 


latter  favors  deposit. 

Results  of  De- 
posit.— The  main  re- 
sults of  deposit  are 
changes  in  river- 
courses  ;  and  the  for- 
mation of  bars  and 
deltas. 

Clianges  In  river- 
courses  are  frequent 
effects  of  deposit. 
They  occur  especially 
in  rivers  that  flow 
through  alluvial  lands. 
Very  often  the  course 
of  such  streams  is 
marked  by  what  are 
called  sinuosities,  or 
sharp  cuiwes  resembling  the  letter  S.  The  lower 
Mississipjii  presents  a  striking  illustration  of 
this.     [See   diagram.]     lu  some  cases  portions  of 


the  land  are  carried  from  one  side  of  the  river  to 
tiie  other,  giving  rise  to  the  important  question  to 
whom  docs  the  land  so  transferred  belong. 

Sometimes,  as  when  a  river  is  unusually  high,  it 
may  make  for  itself  a  straight  cour.so  instead  of 
following  its  old  curves.  The  impetus  of  the 
swollen  waters  forces  them  through  the  soft  clay 
banks.  The  jjortion  of  the  old  channel  that  is 
abandoned  is  closed  by  silt  at  each  end,  and  be- 
comes a  lake. 
y^  Bars. — But  by  far  the  most  imjoortant  cases  of 
deposition  are  those  which  occur  at  the  mouths  of 
rivers.  Here  the  current  of  the  stream  is  checked 
by  the  mass  of  the  ocean  waters,  or  by  the  in- 
coming tide.  Along  the  line  of  meeting,  it  is  clear 
that  there  will  be  comparatively  little  movement, 
and  in  consequence  there  will  be,  in  the  case  of 
large  rivers,  vast  deposits  of  sediment.  This  is 
the  process  by  which  bars  at  the  entrance  of 
harbors  are  formed. 

The  Mississippi,  and  all  the  rivers  of  the  United 
States  that  flow  directly  into  the  Atlantic  Ocean, 
have  bars. 

So  great  is  the  amount  of  solid  matter  brought  down  by 
the  Mississippi  that  a  bar  no  less  than  two  and  a  quarter 
miles  in  breadth  was  formed  off  one  of  its  outlets  called  the 
South  Pass.  Fleets  of  vessels  more  than  fifty  in  number 
might  sometimes  be  seen,  detained  on  the  bar  for  weeks, 
waiting  for  a  chance  to  go  to  sea.  or  enter  the  Pass.  The 
operation  of  towiug  a  ship  into  the  deep  waters  of  the  GuU 
occupied  days,  and  in  some  cases  weeks. 

In  1875  Captain  Eads,  by  the  authority  of  Congress, 
constructed  jetties  or  long  walls,  which  narrowed  and  con- 
fined the  current,  and  thus  gave  it  greater  velocity,  and,  of 
course,  greater  power  to  scour  out  the  channel  and  cany  off 
the  sediment  into  deep  water.  A  similar  project  has  been 
proposed  for  keeping  the  mouth  of  the  Danube  free  from 
obstructions. 


^^ 


SINUOSITIKS    OF    TUE    MISSISSIPPI. 


Deltas. — Then  ajrain.    when    the   river    waters 


encounter  the  waters  of  the  sea,  the  check  to  their 
velocity  will  extend  some  distance  up  the  stream. 
Hence  deposits  are  likely  to  occur  near  the  mouths, 
aiul  some  distance  above  the  mouths,  of  all  silt- 
bearing  rivers.  In  this  way  are  formed  in  the 
course  of  ages  what  are  termed  the  deltas  of  rivers. 

The  Mississippi,  the  Nile,  the  Ganges,  the 
Orinoco,  the  Danube,  the  Volga,  and  many  other 
rivers  which  flow  into  inland  seas  or  gulfs  protected 
from  the  sweeps  of  the  tides  and  ocean  currents, 
are  famous  for  their  deltas. 

But  where  there  is  a  very  strong  littoral  current, 
it  sweeps  off  the  sediment  as  fast  as  it  enters  the 
sea,  and  there  is  no  delta  formed.  This  is  the 
case  with  the  Amazon,  the  Eio  de  la  Plata,  and 
with  all  the  American  rivers  that  empty  into  the 
Pacific  Ocean. 

The  area  of  deltas  is  often  very  large.  That  of 
the  Mississijipi  is  about  12,000  square  miles.     One 


\ 


48 


WATERS    OF    THE    LAND. 


third  of  it  is  still  in  process  of  formation,  being  as 
yet  only  a  sea  marsh. 

Branc}dng  of  Rivers  in  Deltas. — Not  alone  is  sediment 
deposited  upon  tlie  bed  of  rivers,  Init  also  upon  tlieir  banks. 


OW    WATER 


SUCTION     Uf 


This  has  the  effect  of  raising  the  banks  above  the  general 
level  of  the  neighboring  country.  In  some  portions  of  their 
course  both  the  Mississippi  and  the  Po  are  above  the  adja- 
cent fields.  The  land,  therefore,  slopes  from  the  river  on 
either  side,  and  one  goes  up  to  it  instead  of  down  to  it 


DELTA    OF    MISSISSIPPI. 

Now  if  we  bear  this  in  mind,  and  remember,  also,  that 
the  natural  bank  of  the  river  is  only  a  mound  of  sediment, 
we  shall  see  how  readily,  in  ease  of  flood,  the  river  may 
divide  into  branches  and  make  for  itself  new  outlets.  This 
is  to  be  observed  in  all  delta  regions.  It  is  admirably  shown 
in  the  ease  of  the  Mississippi  delta  in  the  accompanying 
illustration. 

This  branching  of  rivers  in  passing  through  their  deltas 
serves  to  explain  why  many  rivers,  such  as  the  Nile,  the 
Mississippi,  the  Ganges  and  others,  have  more  than  one 
outlet. 

A  4.  Relation  of  Rivers  to  Ocean  Life. — 

When  the  rivers  have  discharged  their  waters  into 
the  sea,  they  have  not  yet  finished  their  task. 
Sea-shells  and  coral-rocks  are  formed  chiefly  of  the 
limestone  which  is  dissolved  and  gathered  by  the 
rains  and  rnnning  waters  from  the  mountains, 
plains  and  valleys. 

Of  materials  thus  collected  and  brought  from 
Upper  Egyjit  by  the  Nile,  and  from  the  mountains 
of  Asia  by  the  great  rivers  of  India  and  China,  or 


from  the  peaks  of  the  Andes  by  the  Amazon — of 
such  materials  the  great  whale  and  all  the  fish  of 
the  sea  form  their  bones,  the  pearl  oysters  make 
their  jewels,  the  sea^conch  its  shell,  and  the  coral 
jiolyps  their  evergreen  islands. 

Water  is  thus  seen  to  be  one  of  the  most  wonderful  and 
benign  agents  in  the  terrestrial  economy.  It  is  as  marvel- 
lous in  its  properties,  in  its  adaptations,  and  in  the  perpetual 
development  of  the  most  beautiful  phenomena,  as  is  the  fire 
on  the  hearth.  It  not  only  performs  the  offices  that  are 
familiar  to  us  all,  and  which  have  almost  ceased  to  be 
observed,  or,  when  observed,  have  ceased  to  surprise  us, 
but,  ever  in  a  thousand  unfamiliar  and  hidden  ways,  it  is 
fulfilling  the  beneficent  will  of  Him  who  created  it. 

5.  Lakes. — The  formation  of  lake-basins  may 
be  ascribed  to  various  causes.  Of  these  the  follow- 
ing is,  perhaps,  the  most  frequent.  When  the 
surface  of  the  earth  was  crumpled  as  described  on 
page  28,  depressions  of  greater  or  less  depth  were 
necessarily  formed.  Some  of  them,  receiving  the 
rainfall  drained  from  neighboring  slopes,  became 
the  basins  of  lakes. 

Fresh-wateb  Lakes. — In  the  case  of  lakes 
situated  in  cool  or  damp  regions  precipitation  is  in 
excess  of  evaporation,  or,  in  other  words,  the 
amount  of  rain  falling  in  the  vicinity  of  such 
lakes,  and  carried  into  them  by  streams,  is  greater 
than  the  amount  of  water  taken  up  from  the 
surface  by  evaporation.  They  gain  more  than 
they  lose. 

Clearly,  therefore,  there  will  come  a  time  when 
an  overflow  must  occur.  The  waters  that  no 
longer  can  be  contained  by  the  lake-basin,  will 
break  through  the  rim  at  some  weak  point,  and 
form  for  themselves  a  channel  to  the  sea.  In 
doing  this  they  will  sometimes  cut  pathways 
through  the  densest  rock,  or  burst  through  the 
barriers  of  the  everlasting  hills.  Hence  rapids 
and  waterfalls,  water-gaps,  gorges  and  caQons. 

Salt  Lakes. — In  the  case  of  lakes  situated  in 
regions  of  great  warmth  and  dryness,  the  amount 
of  water  evaporated  is  sometimes  equal  to  that 
which  is  supplied,  and  sometimes  greater.  As 
fast  as  the  water  is  poured  in  by  the  rivers  it  is 
carried  away  in  the  form  of  vapor  and  clouds. 
Such  lakes  are  never  filled  to  overflowing,  and, 
consequently,  have  no  outlets. 

T7ie  ivater  of  lakes  having  no  outlets  is  commotily 
salt.  The  toater  of  lakes  having  outlets  to  the 
sea  is  fresh. 

Explanation.  — Elvers  carry  into  lakes,  in  solution, 
many  saline  materials,  of  which  cue  of  the  most 
abundant  is  chloride  of  sodium  (common  salt). 
This  is  present  in  ordinary  river  water,  although 
it  cannot  be  tasted  ;  but  if  a  large  quantity  of  such 
water  were   evaporated,  a  small  amount  of  salt 


WATERS  OF   THE    LAND. 


49 


YELLOWSTONE    I.AKE. 


would  be  loft  liehiml.  Thus  it  is  clear  that  if  a 
lake  have  an  outlet,  not  only  is  its  superfluous 
water  removed,  but  the  salts  brought  in  are  also 
taken  out. 

On  the  other  hand,  if  a  lake  have  no  outlet,  then, 
while  the  water  brought  in  is  removed  by  evajjora- 
tion,  the  salt  introduced  remains  behind.  Thus 
lakes  having  no  outlet  may  be  compared  to  the 
evaporating  vats  or  troughs  in  which,  as  at  many 
points  on  the  shores  of  the  Mediterranean  Sea, 
water  is  boiled,  or  evaporated  by  solar  heat  in  the 
manufacture  of  salt.  The  water  passes  off,  the 
salt  remains.  Hence,  year  after  year,  salt  lakes 
become  Salter. 

Conspicuous  examples  of  salt  lakes  arc  the  Great  Salt 
Lake  and  the  Dead  Sea.  Both  of  these  are  heavily  charged 
with  saline  ingredients.  The  water  of  the  Dead  Sea  is 
about  one  fifth  heavier  than  that  of  the  ocean,  and  sustains 
the  human  body  so  that  it  cannot  sink  in  it.  From  its 
great  salinity  the  Dead  Sea  is  often  called  the  Sea  of  Salt. 
But  the  Jordan,  which  supplies  it,  is  of  course  fresh. 

The  Dead  Sea  is  situated  in  a  depression  remarkable  for 
its  intense  heat,  and  the  region  in  which  the  Great  Salt  Lake 
lies  is  very  remarkable  for  the  dryness  of  its  atmosphere. 
In  the  case  of  both  these  lakes,  therefore,  evaporation  pro- 
ceeds at  an  enormous  rate. 

Inland  Seas. — Some  inland  bodies  of  salt 
water,  however,  have  evidently  been  at  one  time 
parts  of  the  ocean.  These  are  proj)erly  designated 
inland  seas.  The  most  remarkable  of  them  are 
the  Caspian  and  Aral. 

When  the  Arctic  Ocean  extended,  as  geologists 
believe  it  did,  southward  as  far  as  the  mountains 
of  Persia,  these  two  seas  and  many  neighboring 
bodies  of  salt  water  were  included  within  its  limits. 
Seals  and  certain  fish,  which  are  inhabitants  of 
oceanic  waters,  are  found  even  yet  in  the  Caspian. 

Like  other  salt  lakes  these  inland  seas  have  no 
outlet.  The  Volga,  the  largest  river  in  Europe, 
and  the  Ural   pour   volumes   of    water  into  the 


Cas])ian,  yet  its  level  does  not  rise.  The  Sea  of 
Aral  receives  the  Oxus  and  the  Jaxartcs  ;  yet  its 
level  seems  actually  to  be  lower  than  formerly. 

Many  small  salt  lakes  entirely  evaporate  during 
the  summer,  and  leave  their  beds  covered  with 
saline  incrustations.  From  the  dry  bed  of  Lake 
Elton,  in  the  Cas]iian  region,  100,000  tons  of  salt 
are  annually  gathered. 

G.  Offices  of  JOaJccs. — Lakes  are  reseiToirs 
for  the  rivers.  They  hold  the  waters  back  in  time  of 
flood,  and  give  them  out  in  time  of  drought.  They 
thus  heljj  to  maintain  a  constant  rate  of  discharge 
and  a  uniform  stage  of  water  in  the  rivers.  Hence 
the  Niagara,  the  St.  Lawrence,  the  Nelson,  Mac- 
kenzie, and  other  rivers,  that  are  fed  by  large  lakes, 
never  overflow  so  as  to  devastate  with  floods  the 
country  through  which  they  run. 

On  the  other  hand  the  lower  Mississippi  is  sub- 
ject to  frequent  iniindations,  because  it  is  swelled 
by  the  floods  of  its  principal  tributaries,  and  there 
are  no  lakes  to  hold  back  the  surplus  waters. 

Lakes  again  are  sources  from  which  supplies  of 
vapor  are  obtained,  to  be  gathered  into  clouds,  and 
in  the  form  of  dew  or  rain  to  water  the  land. 

7.  Geograjihical  Distribution  of  Lakes. 

— In  North  America  are  found  the  vast  bodies  of 
fresh  water  which  are  called  the  "  Great  Lakes." 
The  northern  jiart  of  the  Great  Central  Plain  of 
the  continent  abounds  in  lakes,  of  greater  or  less 
magnitude.  In  the  Basin  between  the  Rocky 
Mountains  and  the  Sierra  Nevada  there  is  a  region 
of  saline  Likes. 

In  Europe,  the  great  lake  region  lies  in  Northern 
Russia  and  Scandinavia.  Ladoga  and  Onega, 
Wener  and  Wetter  are  the  largest  lakes  of  the 
continent.  Those  of  the  Alps,  Como,  Maggiore, 
Geneva  and  others  are  comparatively  small,  but 
famed  for  their  beauty. 


5° 


DRAINAGE 


2.  Bivers. 


Asia  is  noted  for  the  size  and  number  of  its  salt 
lakes.  The  Caspian,  Aral  and  Dead  seas  are 
examples.  Of  fresh  water  lakes  Asia  has  few. 
Lake  Baikal,  however,  400  miles  in  length,  may  l)c 
compared  with  our  own  Lake  Superior. 

Africa  rivals  North  America  in  the  magnitude 
of  her  great  lakes.  Victoria  and  Albert  Nyanza, 
Tanganyika  and  Nyassa  are  the  largest. 

South  America  has  two  lakes  of  importance, 
Titicaca  and  Maracaybo.  Australia  is  nearly 
destitute  of  lakes. 

TOPICAL   ANALYSIS. 

n.    WATERS  OF   THE   LAND. 

1.  Springs. 

How  cauped.    ArtePian  wells. 

Interniitteut  springs.    How  caused. 

Hot  springs  and  Geysers.  Forces  by  which  the 
water  is  ejected.  Mineral  springs.  Common  in- 
gredients. 

Dow  formed.    Eiver-systems.    Cataracts.    Rapids. 

Waterfalls.    Noted  falls. 
Offices  of  rivers. 

3.  How  Bivers  change  the  surface  of  the  Earth. 

Erosion.  How  brought  about.  Effects  on  eroded 
material.    Gorges  and  caiions. 

Transportation.  Transporting  power,  how  in- 
creased. Quantity  of  matter  carried  down  by  the 
Rhone  and  the  Mississippi.  Deposit  of  eroded 
material,  by  what  occasioned. 

Results  of  deposit.  Changes  in  river-courses, 
how  caused.  Bars,  how  formed.  Deltas,  how 
formed.  Remarkable  deltas.  Formation  of,  how 
prevented  in  some  cases.    Branching  of  rivers. 

4.  Belation  of  Bivers  to  Ocean  Life. 

5.  Lakes. 

Formation  of.  Cause  of  overflow.  Salt  lakes. 
Cause  of  saltness.    Examples.    Inland  seas. 

6.  Offices  of  Lakes. 

7.  Distribution  of  Lakes. 

In  each  of  the  continents. 

Test  Questions.— If  the  soil  were  everywhere  equally  permeable  to 
water,  how  would  that  affect  the  springs  ?  What  kind  of  springs  may 
rise  higher  than  their  source,  and  wliy?  Why  are  mineral  springs  so 
called  ?  How  can  tlic  water  supplied  by  rivers  make  the  ocean  salter  ? 
Why  is  the  St.  Lawrence  no't  subject  to  floods?  Largest  inland  sea  in 
the  world  f    Largest  body  of  fresh  water  ? 


III.  DEAINAGE. 

1.  Advantages  of  I>rainaffe.~T\\Q  sec- 
ond great  ofiBce  of  rivers  is  to  effect  the  drainage 
of  the  land. 

Any  portion  of  the  globe,  to  be  well  adapted  for 
human  occupation,  requires  to  be  drained.  As  a 
rule  crops  do  not  flourish  in  a  cold,  damp  soil ;  and 


precisely  so  human  health  and  strength  cannot  in 
general  be  maintained  where  the  ground  is  always 
wet.     The  vicinity  of  swamps  is  unliealthy. 

For  this  reason  a  very  large  area  of  the  sunny 
peninsula  of  Italy,  called  the  Campagna,  is  almost 
uninhabited.  From  the  days  of  ancient  Rome 
until  now  it  has  remained,  owing  to  the  level 
nature  of  the  land  and  the  consequent  absence  of 
any  stream  into  which  the  waters  might  be 
directed,  a  vast  swamp  and  a  breeding  ground  of 
pestilence. 

.  2.  Hoiv  Drainage  is  Effected.— Tir&m&g's. 

is  accomplished  by  two  combined  causes  :  (1)  un- 
evenness  of  the  land  ;  (2)  the  flow  of  rivers. 

The  mountains  and  slopes  of  every  country 
determine  in  a  large  measure  the  number  of  its 
water-courses,  their  length  and  direction,  and  the 
velocity  of  their  currents — in  a  word,  their  capacity 
for  carrying  off  superfluous  rain-water. 

The  rivers  are  the  channels  through  which  the 
water  carried  from  the  sea  in  the  form  of  vapor 
and  rained  upon  the  land  finds  its  way  back  to 
the  sea.  Every  running  stream  may  therefore  be 
regarded  as  a  kind  of  rain-gauge,  which  measures, 
in  a  general  way,  the  quantity  of  rain  that  falls 
upon  the  valley  which  it  drains. 

The  region  drained  by  a  river-system  is  called 
the  river-buain.  The  basins  of  large  streams  are 
hundreds  of  thousands  of  square  miles  in  area. 
That  of  the  Mississippi  contains  nearly  1,250,000 
square  miles. 

The  limits  of  a  river  basin  are  defined  by  what 
are  termed  wetter-sheds,  i.e.,  water-divides,  shed 
being  from  a  German  word  meaning  to  divide.  A 
water-shed  is  a  line  of  elevation,  sometimes  lofty 
and  sometimes  low,  which,  like  the  ridge  of  a  roof, 
divides  the  rain  as  it  falls,  and  causes  one  portion 
to  descend  one  slope  of  a  country  or  continent,  and 
the  other  portion  another. 

If  on  a  map  of  North  America  you  trace  a  pencil  line 
round  the  sources  of  all  the  rivers  that  pour  into  the  Mis- 
sissippi from  the  Appalachian  slope  on  the  one  side,  and  from 
the  Rocky  Mountain  slope  on  the  other,  you  will  have 
marked  out  the  water-sheds  which  define  the  eastern  and 
western  limits  of  the  Mississippi  basin. 

The  aggregate  amount  of  water  discharged  into 
the  ocean  by  all  the  rivers  of  the  world  is  com- 
puted at  more  than  two  and  a  half  million  cubic 
yards  per  second.  All  this  volume  of  water,  too 
vast  for  us  to  conceive  of,  is  being  incessantly 
removed  from  the  surface  of  the  earth,  so  as  to 
reader  and  keep  it  suitable  to  be  the  abode  of  man. 
Tliis  shows  how  busily  and  grandly  the  terrestrial 
machineiy  works. 

TxuNDATiONS. — The  inundations  which  occa- 
sionally submerge  large  areas  of  land,  and  are  so 


I 


CONTINENTAL   DRAINAGE. 


SI 


destructive  to  life  and  property,  occur  where  the 
quantity  of  water  to  be  removed  exceeds  the  capac- 
ity of  tlie  draining  rivers.  Many  rivers,  as  the 
Nile,  the  Orinoco  and  the  Mississippi,  arc  subject 
to  periodical  overflow.  So  extensive  are  the  inun- 
dations of  the  Po  that  the  Italian  engineers  have 
actually  proposed  a  scheme  for  cutting  an  artificial 
channel  to  be  used  in  case  of  emergency. 


TOPICAL   ANALYSIS. 


m.    DRAINAGE. 


1.  Advantages  of  drainage. 

2.  How  drainage  is  Effected. 

River-basins.    Water-sheds.    Quantity  of  water  de- 
livered by  rivers.    Cause  of  inundations. 

Test  Questions. — Wliich  of  the  oceans  receives  the  greatest  amount 
of  drainage?  What  ocean  is  without  a  single  river  dowing  into  it,  so 
lar  as  liuown  ? 


IV.  CONTINENTAL  DRAINAGE. 

1.  North  America. — The  four  bounding 
waters  of  North  America  are  the  Arctic,  Atlantic, 
and  Pacific  Oceans,  and  the  Gulf  of  Mexico.  These 
receive  the  di'ainage  of  the  continent. 

Tht  great  water-shed  is  the  Rocky  Mountain 
system.  It  acts  like  the  ridge-pole  to  the  roof  of 
a  house,  shedding  the  water  to  the  east  and  the 
west.  -AJl  the  region  lying  westward  of  it  is 
drained  into  the  Pacific  and  into  Behring  Sea  by 
the  Colorado,  the  Columbia,  the  Frazer,  the  Yukon 
and  other  rivers  of  less  importance. 

East  of  the  Eocky  Mountains  the  continent  is  di- 
vided by  the  Height  of  Laud  and  the  Appalachian 
Mountains  into  three  slopes  :  a  northern  inclining 
toward  the  Arctic  Ocean  ;  an  eastern  toward  the 
Atlantic ;  and  a  southern  toward  the  Gulf  of 
Mexico. 

The  region  lying  north  of  the  Height  of  Land 
is  drained  by  the  Mackenzie,  the  Saskatchewan, 
and  certain  other  streams  which  enter  Hudson 
Bay.  Southward  of  the  Height  of  Land  we  have 
the  great  basin  of  the  Mississippi,  the  drainage  of 
which  is  poured  into  the  Gulf.  This  basin  em- 
braces all  that  enormous  area  which  lies  between 
the  Rocky  Mountains  on  the  west,  and  the  Appa- 
lachians on  the  east. 

The  amount  of  water  carried  by  the  Mississippi  from  this 
region  into  the  Gulf  of  Mexico  every  second  is  675,000  cubic 
feet,  enough,  in  other  words,  to  cover  about  18  acres  of 
ground  to  the  depth  of  a  foot.  We  can  see  from  this  how 
soon  the  Mississippi  basin  would  become  a  desolate  swamp, 
if  it  were  a  dead  level  untrenched  by  its  mighty  system  of 
rivers. 

The  eastern  slope  of  the  continent,  including 
the  terraced  plateau  occupied  by  the  Great  Lakes, 


is  drained  by  the  St.  Lawrence  and  by  a  series  of 
rivers  large  and  small  which  flow  from  the  Appa- 
lachians to  the  Atlantic. 

2.  South  Atuerica.—The  drainage  of  South 
America,  like  that  of  North  America,  is  mainly 
effected  by  one  river  system.  The  crest  of  the 
Andes  is  the  great  water-shed.  It  lies  along  the 
western  edge  of  the  continent.  Hence  the  drain- 
age has  in  general  an  easterly  flow. 

The  eastern  slope  embraces  nearly  the  whole  of 
the  continent.  It  is  naturally  divided  into  three 
great  river  basins,  those  of  the  Orinoco,  the  La 
Plata  and  the  Amazon.  The  last  contains  the 
greatest  river  system  on  the  globe. 

The  Amazon  discharges  six  times  as  much  water  as  the 
Mississippi.  In  respect  to  volume  it  is  the  largest  river  in 
the  world.  It  rises  in  the  beautiful  little  lake  of  Liauricocha, 
high  up  among  the  Andes.  Descending  by  falls  and  rapids, 
it  reaches  the  alluvial  country  below,  and  then  becomes  a 
stream  navigable  for  large  steamers  from  the  foot  of  the 
mountains  to  the  sea,  a  distance  of  about  2,200  miles. 

So  great  is  the  force  of  its  current  that  its  fresh  waters 
are  carried  a  distance  of  about  200  miles  into  the  sea.  An 
ocean  current  passes  near  its  mouth,  and  sweeps  away 
sediment  as  fast  as  the  river  brings  it  down.  Thus  the 
river's  own  current  and  the  ocean  current  prevent  the 
formation  of  a  bar. 

The  western  slope  of  the  continent  is  steep  and 
narrow.  There  is  no  room  for  long,  and  no  water 
for  large  rivers.  The  Pacific  receives  only  a  few 
small  mountain  torrents,  fed  by  the  melting  snows 
of  the  Andes. 

3.  Europe. — From  a  jjoint  in  the  Ural  Moun- 
tains at  about  latitude  61°  north,  to  the  Valdai 
Hills,  thence  in  a  south-westward  direction  through 
Central  Europe  down  to  the  soutlicrn  shores  of 
Spain,  an  irregular  lino  may  be  traced  which  will 
separate  Europe  into  two  great  sIojdcs.  The  one 
inclines  to  the  northwest,  the  other  to  the  south- 
east. 

All  the  rivers  have  one  or  the  other  of  these  two 
general  directions ;  and  the  continent  is  drained 
into  the  Mediterranean,  the  Adriatic,  the  Black 
and  Caspian  Seas  on  the  one  side ;  or  into  the 
Atlantic  and  Arctic  Oceans,  and  the  North, 
Baltic  and  White  Seas  on  the  other. 

The  region  of  the  Alps  is  drained  by  four 
streams,  the  beautiful  Rhine  of  the  Germans,  the 
Rhone,  the  Danube  and  the  Po  ;  the  drainage  of 
the  Low  Plains  is  accomplished  by  a  number  of 
rivers,  among  which  the  Volga,  the  Don,  the 
Dnieper  and  the  Dniester  are  conspicuous. 

4.  Asia. — The  continent  of  Asia,  like  that  of 
Euroije,  may  be  regarded  as  consisting  of  two 
great  slopes,  one  having  a  general  incline  toward 
the  north,  the  other  toward  the  south  and  east. 


52 


CONTINENTAL   DRAINAGE. 


Beginning  on  the  western  shore  of  Asia  Minor, 
a  line  may  be  drawn  to  Mount  Ararat,  thence 
along  the  crests  of  the  Elburz  and  Hindoo  Koosh 
Mountains,  thence  north-eastwardlj  to  the  Sea  of 
Okhotsk,  which  will  rejjresent  tlie  great  water-shed 
of  the  continent. 

Southeast  of  this  line  the  Euphrates  and  Tigris, 
the  Indus,  Ganges,  the  Yang-tse-Kiang,  the 
Hoang-IIo  and  Amoor  carry  the  drainage  to  tlie 
soutliward  and  eastward  into  the  seas  and  bays  of 
the  Pacific  and  Indian  Oceans. 

On  the  nortliern  side  of  the  line  nearly  every 
important  river  flows  in  a  northerly  direction  into 
tlie  Arctic  Ocean. 

5.  Africa. — The  drainage  of  Africa  is  accom- 
plished in  the  main  by  the  four  great  river  systems 
of  the  Nile,  the  Niger,  the  Congo  and  the  Zambesi. 
Much  of  the  surplus  water  of  the  continent,  how- 
ever, is  removed  by  evaporation. 


G.  Australia. — Australia  is  scantily  supplied 
with  rivers.  The  Murray  and  its  tributaries  are 
the  only  water-courses  of  importance,  and  they  are 
often  reduced  in  tlie  dry  season  to  a  mere  cliain  of 
ponds  and  creeks. 

TOPICAL   ANALYSIS. 
IV.    CONTINENTAL  BRAINAGE. 


Physical  divisions  of  tlie  surface 
and  resulting  drainage. 


1.  North  America. 

2.  South  America. 

3.  Europe. 

4.  Asia. 

5.  Ai'rica. 

6.  Australia. 


Test  Questions.— Largest  river  that  flows  into  the  Atlantic  ? 
Pacific  ?  Into  Ihu  Indian  Ocean  ?  Largest  river  in  the  world  that  does 
not  reach  an  ocean  r  What  river  of  North  America  corresponds  in 
magaitnde  and  location  to  the  Orinoco  of  South  America  »  To  tlie  La 
Platu  t  Besides  rivers,  and  rain  or  snow,  do  you  know  of  anything 
else  that  supplies  freeh  water  to  the  Ocean  ? 


The  most  interesting  feature  in  the  drainage  system  of 
Africa  is  the  river  Nile.  But  for  it  Egypt  would  be  as 
barren  as  the  Great  Desert  of  Sahara.  The  river  is  formed 
by  the  junction  of  two  streams  called  the  White  and  the 
Blue  Nile.  The  former  issues  from  the  Equatorial  Lakes. 
The  latter  rises  among  the  hills  and  tlie  table-lands  of 
Abyssinia. 

During  June,  July,  and  August  the  rains  pour  down  in 
torrents  upon  the  regions  drained  by  these  streams.  Each 
is  flooded.  Uniting  at  Khartoom  the  descending  torrents 
reach  Cairo  by  the  middle  of  June,  and  during  the  latter 
part  of  summer  and  in  the  autumn  the  whole  of  Egypt  is 
under  water. 

As  the  flood  subsides  a  layer  of  fertilizing  sediment  is 
deposited  upon  the  land.  Most  of  it  has  been  washed  down 
from  the  Abyssinian  hills  by  the  Blue  Nile,  which  takes  its 
name  from  the  color  which  the  sediment  imparts  to  its  waters. 


V.  THE  SEA. 

1.  Extent  of  tlie  Sea, — Nearly  three- 
fourths  of  tlie  earth's  surface  are  covered  by  water. 
Tliis  surface  comprises,  in  round  numbers,  an 
area  of  197,000,000  square  miles,  of  which  about 
53,000,000  are  land,  and  14i,000,000  water.  All 
of  the  land,  except  13,000,000  square  miles,  is  on 
the  north  side  of  the  equator.  The  northern 
hemisphere  therefore  contains  three-fourths  of  all 
the  known  land,  and  two-fifths  only  of  the  water- 
surface,  of  the  world. 

The  extent  of  water  that  is  visible  to  the  eye  at  one  time 
is  not  great.     If  we  stand  on  the  shore  and  look  seaward. 


THE    SEA. 


53 


i 


our  view  is  closed  in  by  a  line  in  which  sea  and  sky  appear 
to  meet.  To  this  line  we  give  the  name  horizon,  i.e.,  bound- 
ing line.  Us  distance  I'rom  us  depends  on  our  elevation. 
If  we  occupy  a  position  which  is  elevated  six  feet  above  the 
sea-level  our  horizon  will  be  three  miles  off.  It  we  ascend 
a  bluff  or  lighthouse,  and  so  gain  a  point  about  100  feet 
high,  our  horizon  will  be  twelve  miles  distant. 

2.  Saltness  of  the  <S^«.— Various  solid 
ingredients  are  found  dissolved  in  sea  water.  Of 
these  the  most  abundant  is  what  we 

call  common  salt.  Others  are  cer- 
tain compounds  of  lime,  magnesium, 
potassium  and  iodine.  The  solid 
ingredients  may  be  estimated  on  an 
average  as  about  one-thirtieth  part 
of  the  whole  by  weight. 

Though  there  is  little  variation  from  the 
average,  yet  it  seems  to  be  well  ascertained 
that  within  the  regions  of  the  trade  winds 
(see  p.  76.)  the  jiroportion  of  saline  ingre- 
dients is  greater  than  elsewhere.  This  is 
natural,  since  in  that  region  evaporation* 
is  at  its  maximum.  North  and  south  of 
the  trade-wind  region  there  appears  to 
be  a  progressive  diminution  of  saline  mat- 
ter as  the  poles  are  approached. 

3.  Oviffin  of  Saltness, — Sup- 
posing the  water  of  the  sea  to  have 
been  originally  all  fresh,  it  is  easy 
to  see  how  in  the  lapse  of  time  it 
can  have  become  salt.  The  case  of 
the  sea  may  be  compared  to  that  of 
a  lake  with  no  outlet.  All  the  rivers 
run  into  the  sea  and  carry  into  it  im- 
mense quantities  of   saline  matter. 

The  amount  thus  contributed  during  the  past  ages 
of  the  world's  history  would  be  simply  inconceiv- 
able— amply  sufficient  to  account  for  the  present 
saltness  and  density  of  the  waters  of  the  sea. 

Another  theory  is,  that  when  the  vapory  materials  consti- 
tuting the  earth  were  originally  condensed  (see  p.  7),  the 
saline  substances  were  among  the  last  to  be  condensed  and 
deposited.  Following  soon  after  these  watery  vapor  was 
condensejl,  and  falling  as  rain  washed  the  saline  deposits 
into  the  ocean-basin.  According  to  this  view  the  sea  was 
salt  from  the  beginning. 

4.  Color  of  the  Sea. — The  sea  is  green,  or 
blue ;  it  is  sometimes  colored  here  and  there  by 
reddish,  or  whitish,  yellowish,  or  crimson  patches, 
according  to  the  tints  imparted  by  the  color  of  the 
bottom,  by  the  shadow  of  the  clouds,  by  the  ingre- 
dients of  its  waters,  or  by  its  myriads  of  organisms. 


In  certain  jiarts  of  the  Indian  Ocean  the  waters, 
as  seen  from  a  distance,  are  black. 

In  the  Mediterranean,  in  the  Gulf  Stream,  and 
between  the  tropics  generally,  the  sea  waters  arc 
dark  blue  ;  along  the  shores  and  near  the  mouths 
of  great  rivers  and  in  coral  seas  they  are  green. 

Thus  the  sea  assumes  here  and  there  various 
shades  of  color  ;  yet  its  waters,  when  taken  by  the 
tumblerful,  are  as  clear  as  the  purest  crystal. 


rllO.-PHOKESCENT   SEA. 


*  Evaporate  a  small  portion  of  sea  water  until  it  is  very  much  concen- 
trutod.  Then  tnke  a  drop  of  this  concentrated  fluid  and  put  it  on  a  piece 
of  thin  glass  under  a  microscope.  You  will  gee  the  saline  substances 
which  have  given  the  sea  water  its  peculiar  taste  crystallizing  in  regular 
ebapes  as  the  water  gradually  dries  from  the  glass. 


5.  JPhospJiorescence. — In  most  parts  of 
the  sea  the  water  is  phosphorescent.  The  phos- 
phorescence is  caused  by  certain  animalcules, 
which,  like  glow-worms  and  fire-flies  on  the  land, 
have  the  power  of  emitting  light,  some  in  flashes, 
and  some  in  a  steady  glow.  These  little  creatures 
are  invisible  to  the  naked  eye,  but  they  are  as 
multitudinous  as  the  sand,  and  as  beautiful  as  the 
stars. 

In  tropical  seas  and  in  certain  waters  they  tip 
the  waves  with  flame,  and  cover  the  sea  after  dark 
with  sheets  of  light.  As  the  ship  ploughs  these 
waters,  she  leaves  a  bright  streak  far  behind  in  her 
wake. 

Though  we  cannot  see  the  dolphin  and  other  fish,  as  they 
sport  in  the  depths  of  these  phosphorescent  seas,  yet,  by  the 
streaks  they  leave  behind,  we  can  often  track  them  through 
the  water,  as  we  do  rockets  through  the  air.  As  they  chase 
each  other  in  the  mazes  of  their  sport,  these  threads  of  light 
are,  to  those  who  are  fortunate  enough  to  see  them,  among 
the  most  pleasing  wonders  of  the  deep.  They  are  particu- 
larly beautifid  in  the  harbor  of  CaUao. 

6.  Tlie  Temperature   of  the  Sea  is  in 


54 


THE    OCEANS. 


general  highest  near  the  surface.  In  the  equato- 
rial waters  tlie  average  surface  temperature  i.s  about 
80°  Fahr.,  sometimes  rising  in  the  Indian  Ocean  to 
90°  Fahr.,  and  in  the  Red  Sea  to  94°.  Towards 
the  bottom  the  temi)erature  is  depressed.  Indeed, 
near  the  bottom  all  over  the  globe  deep-sea  water 
seems  to  be  about  as  cold  as  that  of  the  Polar  seas. 
The  variations  at  the  same  place  between  the  win- 
ter and  summer  temperature  of  the  sea  rarely  ex- 
ceed 10°.  Thus,  in  Polar  seas,  the  surface-water  is 
seldom  above  42°,  nor  in  equatorial  below  68°. 

7.  Offices  of  the  Sea. — (1)  The  sea  receives 
the  drainage  of  the  land ;  (2)  it  wears  away  or 
builds  up  the  land  ;  (3)  it  supplies  the  atmosphere 
with  moisture  ;  (4)  it  is  one  of  the  great  regulators 
of  climate  ;  (5)  it  is  the  highway  of  the  nations. 
Commerce,  civilization  and  Cliristianity  have  been 
wafted  on  its  bosom  to  the  ends  of  the  earth. 


V 


TOPICAL  ANALYSIS. 


V.    THE   SEA. 


I.  Extent. 


Comparative  sea  area  in  northern  and  southern 
hemispheres.  Extent  of  water  visible  at  one 
time. 


2.  Saltness. 


Due  to  what  inj^cdicuts.  Quantity  of  saline  matter. 
Variation  of  saltucsa  with  distance  from  the 
Equator. 

3.  Origin  of  Saltness. 

4.  Color  of  the  Sea. 

6.  Phosphorescence. 

Cau.se.    Beautiful  effects. 

6.  Temperature. 

Surface  temperature  in  Equatorial  regions.  Deep 
bottom  temperature.    Variation  with  the  season. 

7.  Offices  of  the  Sea. 

Test  Questions.— Why  should  the  sea  be  sallest  where  evaporation 
is  greatest  ?  Why  sho\i]d  it  be  coldest  at  the  bottom,  white  the  land 
grows  warmer  as  we  descend  ?  Why  should  the  Red  Sea  be  warmer 
than  the  Indian  Ocean?  Why  does  not  a  glass  of  sea  water  show  tlie 
same  color  us  the  sea  itself  ? 


VI.  THE  OCEANS. 

1.  The  Oceans. — The  sea  is  one  immense 
Dody  of  water  encircling  the  globe.  It  is,  how- 
ever, divided  by  the  intervening  land  masses,  or 
continents,  into  smaller  bodies,  called  oceans.  Of 
these  the  Pacific  is  the  largest.  It  contains  more 
than  half  the  water  of  the  sea.  Next  in  size,  but 
only  about  half  as  large  as  the  Pacific,  is  the  At- 
lantic. Tlie  Indian  is  the  third  in  area.  The 
Arctic  is  properly  only  an  extension  of  the  Atlan- 
tic, while  the  Antarctic  hardly  deserves  to  be  re- 
garded as  distinct  from  the  main  body  of  the  sea. 


Ocean  Basins. — The  form  of  each  ocean  basin 
depends  naturally  upon  the  sliape  of  the  enclosing 
continents.  The  Pacific  approaches  the  oval  ;  the 
Atlantic  has  been  compared  to  a  long  trough  ;  the 
Indian  is  triangular,  while  tlie  Polar  oceans  cannot 
be  said  to  have  any  describable  shape. 

Of  all  the  oceans  the  Atlantic  is  the  most  marked 
by  indentations  of  its  shores.  The  Asiatic  edges 
of  the  Pacific  and  Indian  oceans  are  also  well  sup- 
plied with  bays  and  border-seas. 

2.  Dejifh  of  the  Oceans. — Two  questions 
connected  with  the  subject  of  ocean  basins  have 
been  within  a  few  years  made  matter  of  accurate 
investigation — their  depth  and  the  nature  of  their 
bottom. 

The  average  depth  of  the  Atlantic  is  about 
15,000  feet.  It  seldom  exceeds  18,000  feet,  or  3i 
miles.  The  deepest  sounding  was  near  the  island 
of  St.  Thomas.  It  was  23,250  feet,  or  rather  less 
than  4^  miles. 

The  average  depth  of  the  Pacific  seems  to  be 
about  the  same  as  that  of  the  Atlantic.  It  has, 
however,  deeper  abysses.  Soundings  of  4^  and  5 
miles  have  been  obtained.  These  are  the  very 
deepest  that  have  been  accurately  measured. 

3.  The  Bottom  of  the  Ocean  is,  like  the 
land,  diversified  with  hill  and  dale.  Vast  plateaus, 
banks,  and  shoals  spread  themselves  out;  and 
mountains  rise  from  the  ocean  depths  far  more 
abruptly  than  they  do  on  the  land. 

San  Domingo  and  many  other  islands  of  the  sea 
rise  from  the  bottom  to  the  surface  almost  per- 
pendicularly. The  Silla  de  Caracas,  on  the  other 
hand,  which  is  the  steepest  mountain  in  the  world, 
rises  at  an  angle  of  53°. 

Bed  of  the  Atlantic. — The  bed  of  the  Atlan- 
tic has  been  more  thoroughly  examined  than  any 
other.  It  seems  to  consist  of  two  nearly  parallel 
valleys  extending  north  and  south  and  separated 
by  a  lofty  dividing  ridge.  The  islands  which  are 
scattered  along  its  length  are  the  summits  of  this 
ridge.  That  portion  of  the  Atlantic  bed  to  which 
the  name  of  Telegraphic  Plateau  has  long  been 
given  is  of  sj^ecial  interest.  This  ijlateau  stretches 
entirely  across  from  Newfoundland  to  Ireland,  at 
an  average  depth  of  somewhat  less  than  two  miles. 

If  we  imagine  ourselves  walking  across  it  from  Newfound- 


NoTE. — Tlie  practical  value  of  tlie  information  derived  from  the 
Atlantic  deep-sea  houndinffs  was  early  appreciated  by  the  author  of  this 
book.  Almost  as  soon  as  the  results  of  the  soundings  were  made  known 
to  him,  he  saw  that  the  laying  of  a  telegraphic  cable  was  a  practicable 
project.  He  was  the  first  to  suggest  and  urge  the  carrying  out  of  this 
scheme,  the  accomplishment  of  which  has  been  one  of  the  grandest 
acliievenients  of  modem  science.  To  Maury  belongs  the  glory  of  having 
pointed  out  a  highway  under  the  waters,  whereby  the  ends  of  the  world 
have  been  brought  into  instantaneous  communication.— The  Reviseb. 


WAVES   AND   TIDES. 


55 


50 

to 

Loii^'lMulo 

r-0 

from 

20 

Green  wicli 

10 

West 

0 

East 

10,000 

0 

10,000 

so  000 

LABRADOR 

■ 

4. 

IREL 

ENGLAND 

^^    NETMERLAN08 

Q 

^ 

^ 

1 

■ 

1^1 

VERTICAL    SECTION    OF    THE    ATLANTIC    OCEAN    AT    52°  NORTH    LATITUDE.      Scale--10  mihs  Icnalh     lOOU/l.  heii/M 


land  to  Ireland,  we  shall  first  descend  by  an  easy  slope  to 
the  Grand  Banks.  Here  the  depth  is  about  1,000  feet. 
Leaving  the  Grand  Banks  we  shall  pass  quite  rapidly  to  the 
depth  of  about  13,800  feet.  Prom  this  point  there  is  not 
much  variation  in  the  depth  for  about  half  way  across  the 


ocean.  When  however,  we  have  performed  half  our 
journey,  wo  shall  ascend  again,  first  rapidly  and  then 
gently,  until  we  reach  the  neighborhood  of  the  British  Isles. 
For  a  distance  of  about  330  miles  westward  of  In/laiid  the 
upward  slope  is  very  gradual  until  we  gain  the  dry  land. 


50  Longitude  West  i(^  from  Greenwich  ?.0 


.pel« 


VERTICAL    SECTION    OF    THE    ATLANTIC    OCEAN    AT    14' 48'    NORTH    LATITUDE.     Scale— 10  miles  length-1000 ft.  hi-iyht 


Bed  of  the  Indian  Ocean. — The  soundings 
thus  far  taken  in  the  Indian  Ocean  seem  to  indicate 
that  the  configuration  of  its  bed  is  not  unlike  that 
of  the  Atlantic. 

It  is  believed  that  two  valleys  similar  to  those 
of  the  Atlantic  traverse  this  ocean.  As  in  the 
Atlantic  they  are  nearly  parallel  and  extend  in  a 
north  and  south  direction,  while  a  ridge  indicated 
by  the  Laccadive,  Maldive  and  Chagos  Islands 
separates  them. 

Bed  of  the  Pacific. — Of  the  bed  of  the  Pacific 
we  have  little  accurate  knowledge.  Judging  from 
the  multitude  of  islands,  great  and  small,  which 
diversify  its  surface,  we  know  that  a  corresponding 
number  of  rock  masses,  miles  in  height,  and 
shaped  like  gigantic  columns,  must  rise  abruptly 
from  its  floor. 

The  cruise  of  the  ship  Challenger  revealed  the 
fact  that  in  the  bed  of  this  ocean  are  the  greatest 
dejjths  hitherto  measured.  One  sounding  gave  a 
depth  of  more  than  5  miles ;  another  about  ii. 
No  complete  survey  has,  however,  been  made  as 
yet. 

TOPICAL   ANALYSIS. 

VI.    THE   OCEANS. 

1.  The  Oceans 

Number  and  relative  size.    Form  of  basins. 
Indentation  of  sliores. 

2.  Depth. 

Of  the  Atlantic.     Of  the  P:icific. 

3.  Bottom. 

General  form  as  compared  witli  the  surface  of  the 
land.  Bed  of  the  Atlantic.  Of  the  Indian  Ocean. 
Of  the  Pacific.  Practical  value  of  deep-sea 
soundings  upon  the  intercourse  of  nations. 


Test  Questions.— How  does  the  average  depth  of  the  ocean  compare 
with  the  average  height  of  the  land  ?  [see  p.  27.]  Why  should  islands 
rise  more  perpendicularly  under  the  water  than  moumainB  do  on  the 
land  ? 


r 


VII.  WAVES   AND    TIDES. 


1.  Waves. — "  The  troubled  sea  that  cannot 
rest "  has  ever  been  the  emblem  of  unending 
movement.  Waves,  tides,  and  currents  incessantly 
disturb  it. 

Waves  are.  caused  by  the  wind. — The  wind 
strikes  with  more  or  less  force  upon  the  surface  of 
the  sea,  and  thus  jjroduces  an  alternate  upward 
and  downward  movement  of  its  waters.  A  mass 
of  water  moved  in  this  way  is  called  a  wave. 
The  elevated  portion  of  the  water  is  called  the 
crest  of  the  wave  ;  the  distance  from  one  crest  to 
another  is  the  Irvadth. 

Wave-movement. — The  rolling  in  of  waves 
upon  the  beach  produces  the  imijres.^ion  that  the 
entire  body  of  water  is  moving  toward  the  land. 
As  we  shall  see,  however,  when  we  come  to  con- 
sider the  subject  of  tides,  it  may  actually  be  reced- 
ing. We  must,  therefore,  distinguish  between 
the  motion  of  the  wave-movement  and  the  motion 
of  the  water. 

To  ilhistrate :  If  we  produce  a  ripple  upon  the 
surface  of  water  in  a  basin,  bath,  or  jiond,  the 
ripple  will  travel  from  end  to  end  of  the  water, 
and  communicate  an  undulating  or  wave-move- 
ment to  each  i)ortion  of  the  surface.  But  the 
water  itself  has  no  progressive  movement. 

The  action  of  a  breeze  upon  a  field  of  wheat, 


5<^ 


WAVES  AND  TIDES. 


or  tall  grass,  illustrates  the  matter  very  forcibly. 
The  wind  jjasscs  over  the  field,  and  eacii  stalk  and 
blade  bends  alternately  down  and  up,  thus  forming 
depressions  and  wave-crests.  Yet  there  is  no 
onward  movement  of  the  stalks.  It  is  only  the 
motion  that  travels. 

Those  portions  of  the  water,  however,  which 
actually  reach  the  shore,  do  possess  an  onward 
movement.  Instead  of  being  driven  against  an 
adjoining  mass  of  water,  they  encounter  the  solid 
bottom.     Thus  the  lower   part   of   their   mass   is 


WEARING    AWAY    OF    THE    ROCKS. 


retarded,  while  the  upper  part  moves  onward, 
curls  over,  and  dashes  as  a  breaker  upon  the 
beach. 

The  Height  of  "Waves  depends  mainly  upon 
the  force  of  the  wind,  and  the  depth  of  the  water. 
In  general  they  are  not  more  than  8  or  10  feet 
high.  The  highest  known  are  those  off  the  Cape 
of  Good  Hope,  where  they  are  said  to  attain  the 
heiglit  of  more  than  40  feet. 

The  Velocity  of  Wave-movements  depends 
(1)  on  the  velocity  and  force  of  the  wind  ;  and  (2) 
upon  the  depth  of  the  water,  and  its  freedom  from 
obstructions.  In  the  open  sea  the  advance  of  a 
wave-movement  is  more  rapid  than  in  one  ob- 
structed with  islands.  The  rate  of  wave-travel  is 
estimated  at  from  15  to  upwards  of  150  miles  an 
hour. 

Effect  of  Wave-movements. — The  wave-move- 
jnents  of  the  ocean  are  incessant.  Even  where  a 
3)erfect  calm  prevails,  there  is  a  ceaseless  move- 
ment of  the  water,  which,  like  a  great  pulse,  keeps 
the  surface  constantly  rising   and   falling.     This 


heaving  is  commonly  known  as  tJie  (jround  swell 
of  the  ocean. 

Waves  affect  the  sin-face  chief y.  The  highest 
waves  in  a  storm  have  no  appreciable  effect  in 
water  more  than  a  quarter  of  a  mile  in  depth.  A 
wave  40  feet  high  and  a  quarter  of  a  mile  in 
breadth  would  not,  in  all  i)robability,  disturb  the 
smallest  grain  of  sand  lying  on  the  sea-bed  at 
a  depth  of  200  fathoms. 

2.  Force   nnd    Wovit   of   Waves. — The 

heaviest  billows  beat  against 
the  rocks  on  the  shore  with  a 
force  varying  from  COO  to  0,000 
lbs.  to  the  square  foot.  They 
dash  the  rocks  to  pieces,  and 
grind  them  into  sand,  which  is 
transported  by  the  currents  of 
the  sea  to  other  parts  of  the 
world. 

All  the  sand,  many  of  the 
stratified  rocks,  much  of  the 
clay  and  soil,  with  which  the 
rocky  skeleton  of  the  earth  is 
clothed,  have  at  one  time  or  an- 
other been  broken  or  j^ulver- 
ized  by  the  action  of  water. 

The  wavps  have  in  many  places 
modified  the  features  of  the  shore  by 
erecting  dunes,  or  shifting  hills  of 
sand.  In  some  cases  harbors  have 
been  filled  up.  Many  fishing  vil- 
lages on  the  shores  of  the  Bay  of 
Biscay  have  been  overwhelmed. 

3.  The  Tides  are  gigantic  wave-movements 
which  affect  the  entire  mass  of  the  sea.  In  a  gen- 
eral way  it  may  be  said  that  two  vast  waves, 
each  having  its  crest  and  its  depression,  to- 
gether encircle  the  globe  from  north  to  south. 
These  two  ceaselessly  chase  one  another  over  the 
broad  expanse  of  the  sea,  occasioning  two  ele- 
vations and  two  dejiressions  of  its  waters  in  the 
course  of  about  twenty-five  hours.*  From  the 
fact  that  these  elevations  and  depressions  occur 
with  regularity  about  one  hour  later  each  day,  and 
thus  rudely  mark  the  time,  they  are  called  tides, 
from  the  Anglo-Saxon  iul,  time. 

The  elevation  or  rising  of  the  water  is  called 
high  or  flood-tide,;  the  depression  or  falling  of  the 
water,  low  or  ebb-tide. 

4.  Theory  of  Tides. — The  tides  are  mainly 
due  to  the  influence  of  the  moon.  The  sun  also  has 
a  tide-producing  power,  but  it  is  insignificant  com- 
pared to  that  of  the  moon,  owing  to  the  fact  that 


/:, 


*The  exact  time  is  twenty-four  hours,  fifty  minutes,  or  what  is 
known  as  a  lunar  day,  i.e..,  the  time  between  the  crossing  of  the  merid- 
ian of  a  place  by  the  moon  and  her  being  on  the  same  meridian  again. 


WAVES    AND   TIDES. 


57 


the  sun  is  400  times  farther  off  from  the  eartli  than 
the  moon  is. 

The  moon  is  comparatively  near  to  the  cartli. 
Let  us  see  then  how,  in  consequence  of  tliis,  slie  af- 
fects its  waters. 

Hiyh  Tides. — As  reiiresented  in  fhc  ilhistration, 
tlie  opposite  sides  of  tlie  eartli  have  high  tide  at 
the  same  time,  and  low  tide  at  the  same  time. 
High  tide  occurs  at  J,  on  the  side  of  the  earth 
toward  the  moon,  for  this  reason ;  the  moon  is 
nearer  to  the  water  on  that  side  of  the  earth  than 
it  is  to  the  centre  of  the  earth.  Hence  the  moon 
attracts  the  water  more  powerfully  than  it  does  the 
earth,  and  the  water  bulges  forward  as  a  high  tide. 

But  why  is  it  high  tide  also  at  B,  on  the  opposite 
side  of  the  earth  ?  In  this  case  the  general  mass 
of  the  earth  is  more  powerfully  attracted  by  the 
moon  than  the  water  is,  and  the  effect  is  as  though 
the  earth  were  drawn  away  from  the  water;  so  that 
here  also  the  water  bulges  forward  as  a  high  tide. 


tide-producing  forces.  Hence  we  have  what  are 
known  as  the  spring  tides.  During  these  the  flow 
is  at  its  maximum.  When,  on  the  other  hand,  the 
moon  enters  her  first  and  last  quarters,  the  two 
forces  do  not  act  in  harmony,  and  we  have  in  con- 
sequence the  tiecqj  tides,  in  which  the  flow  is  greatly 
less  than  in  the  spring  tides. 

/*.  Orif/in  of  the  Tidal-  Wave. — In  pursu- 
ance of  regulations  established  some  years  ago  by 
the  authority  of  the  British  government,  observa- 
tions were  made  upon  the  tides,  night  and  day,  for 
a  whole  month,  in  all  parts  of  the  world.  These 
observations  led  to  the  conclusion  that  the  tidal- 
tvave  has  its  cradle  in  that  great  expanse  of  ocean 
that  surrounds  the  Antarctic  rcgioii. 

6.  3Tovcme}it  of  Tidal-Wave.— StaTtiri:g 
at  the  point  of  its  origin,  let  us  observe  the  progress 
of  the  tidal-wave  as  it  passes  from  ocean  to  ocean 
round  the  globe. 


SPRING    TIDES. 


Low  Tides. — Half-way  between  the  tidal  wave- 
crests  or  high  tides,  there  are  depressions,  as  rep- 
resented in  the  illustration.  These  occur  where 
the  water  is  drawn  away  to  form  the  high  tides. 
They  create  the  low  tides.  Like  the  high  tides 
they  take  place  twice  in  a  lunar  day,  at  intervals 
of  a  little  more  than  twelve  hours. 

Evidence. — Evidence  that  the  moon  chiefly  is 
concerned  in  causing  the  tides  is  to  be  found  in  the 
facts  (1)  that  high  tide  occurs  at  any  place  nearly  at 
the  time  when  the  moon  is  over  the  meridian  of 
the  place ;  and  (2)  that,  at  full  moon  and  new 
moon,  the  tides  are  higher  than  usual. 

Spring  and  Neap  Tides. — A  marked  phe- 
nomenon of  the  tides  is  that  the  intensity  of  the 
movement  varies.  Three  days  after  full  and  new 
moon  the  flow  or  rise  of  the  water  is  far  greater 
than  usual.  This  is  explained  by  the  fact  that 
when  the  moon  is  new,  as  in  the  illustration,  and 
when  she  is  full,  the  sun  and  moon  combine  their 


The  "  chart  of  co-tidal  lines "  on  page  50  will 
be  found  useful  in  doing  this.  These  lines  con- 
nect places  which  have  high  tide  at  the  same  time. 
They  represent  the  crest  of  the  tidal-wave.  In  the 
waters  about  New  Zealand,  the  birth-place  of  the 
tides,  and  to  the  northward  as  far  as  the  Tropic 
of  Cancer,  they  show  that  the  tidal-wave  extends 
nearly  north  and  south.  As  it  advances,  portions 
of  it  are  retarded,  or  deflected  or  even  repelled  by 
reefs,  islands,  or  continental  shores. 

The  deeper  the  water,  the  more  rapid  is  the  rate 
of  the  tidal-wave.  This  is  indicated  by  the  bulg- 
ing of  the  co-tidal  lines.  The  distance  between 
any  two  lines  is  the  distance  traversed  in  an  hour. 

With  our  eye  upon  the  chart,  let  us  now  follow 
the  movements  of  the  tidal-wave  in  the  three  great 
oceans,  the  Pacific,  the  Indian,  and  the  Atlantic. 

Pacific  Ocean. — In  the  Pacific  Ocean  the  tidal 
movement  is  more  regular  than  in  either  the  In- 
The  general  course  of  the 


dian  or  the  Atlantic. 


58 


WAVES   AND   TIDES. 


wave,  however,  iiiste;ul  of  being  due  west,  is  north- 
westward. Tlie  long  crest  extends  aci-oss  the  ex- 
])anse  of  the  ocean,  and  advances  toward  the  sliore 
of  Asia.  In  three  hours  after  it  has  broken  ujron 
tlie  coast  of  New  Zealand,  it  roadies  Sydney  and 
Tokio. 

The  islands  and  continental  masses  on  either 
side  of  the  Pacific  basin  retard  its  movement, 
whereas  in  mid-ocean,  as  indicated  by  the  bulging 
of  the  curves,  it  advances  with  vastly  greater 
rapidity.  When,  for  instance,  its  nortliern  ex- 
tremity has  reached  San  Francisco,  its  centre  has 
bulged  4,000  miles  to  the  westward. 

It  will  be  seen  that  one  portion  of  the  wave  is  reflected  or 
rejielled  in  a  south-easterly  direction  to  the  shores  of  South 
America.     The  cause  of  this  is  not  understood. 

Indian  Ocean. — In  the  Indian  Ocean  we  ob- 
serve the  same  general  phenomena  as  in  the  Pacific. 
The  tidal-wave  advances  to  tlie  north-westward. 
Its  centre  crosses  tiie  main  body  of  the  Indian 
Ocean  with  rapidity.  Its  extremities  are  retarded 
by  the  shores  and  islands  which  it  encounters. 

Atlantic  Ocean. — In  tlie  Atlantic,  as  in  the 
Pacific  and  Indian  Oceans,  the  tidal-wave  has  a 
north-westward  direction.  It  traverses  the  length 
of  the  ocean  from  soutJi  to  north  in  about  twelve 
hours.  It  travels,  therefore,  at  tlie  rate  of  about 
500  miles  an  hour. 

Owing  to  the  narrowness  of  the  Atlantic  basin 
and  the  irregular  contour  of  its  shores,  the  tidal- 
wave  encounters  many  retarding  and  deflecting 
obstacles. 

North  of  the  Equator  a  portion  of  the  wave,  fol- 
lowing the  narrow  channel  between  the  shores  of 
Europe  and  Africa  on  one  side  and  those  of  Green- 
land on  the  other,  assumes  a  north-easterly  direc- 
tion. 

On  the  western  side  of  the  North  Atlantic,  the 
tidal-wave  travels  faster  tlian  on  the  eastern,  be- 
cause, as  is  sujjposed,  this  portion  of  tlie  ocean  is 
deeper  than  the  other.  It  reaches  Newfoundland 
on  the  west  in  latitude  48°  north,  when  it  is  no 
farther  oit  the  east  tlian  Cape  Blanco,  in  latitude 
21°  north,  on  the  African  shore. 

7.  Speed  of  Tidal- Wave.— ^mce  the  tides 
follow  the  moon,  they  have  to  travel  round  the 
earth  from  east  to  west  in  the  same  time  that  she 
does,  viz.,  twenty-four  hours  and  fifty  minutes. 
The  tidal-wave,  therefore,  in  equatorial  seas, 
would,  if  it  were' unobstructed,  and  could  pursue 
a  direct  course,  travel  at  the  rate  of  1,000  miles  an 
hour.  As  a  matter  of  fact,  however,  its  speed  is 
about  500. 

When,  however,  it  comes  near  the  shores  where 
the  water  is  shallow,  a  change  occurs.     The  undu- 


lation is  retarded,  but  the  motion  of  the  water  is 
vastly  increased,  and  it  sweeps  as  a  current  along 
tlie  continental  shores  and  up  the  bays  and  rivers. 
The  current  gains  in  s])eed  as  the  tidal-wave  loses. 
The  current  often  attains  unusual  speed  in  ])ass- 
ing  headlands ;  and  then  the  term  race  is  com- 
monly applied  to  it. 
Sucli  an  accelerated  cur- 
rent moves  from  six  to 
eleven  miles  an  hour. 

In  order  that  the  imagina- 
tion may  not  be  bewildered 
by  the  attempt  to  conceive 
of  water  travelling  with  the 
high  velocity  of  the  tidal- 
wave,  it  should  be  borne  in 
mind  that  the  water  in  mid- 
ocean  has  only  an  impercept- 
ible progressive  motion  ;  it 
is  simply  the  motion  or  un- 
dulation that  travels  at  this 
high  rate  of  speed. 

The  waving  grain,  as  it 
bends  to  the  breeze,  causes 
an  undulation  that  travels 
across  the  field  faster  than 
you  can  run  ;  but  the  stalks 
aie  rooted  ;  they  only  sway 
backward  and  forward  to  the 
breeze.  So  it  is  with  the  sea 
and  its  swell. 

8.  HeifjMof  Tides. 

— In  tlie  middle  of  the 
Pacific  Ocean  the  rise  of 
the  tide  is  sometimes  less 
than  a  foot ;  in  the  At- 
lantic, near  St.  Helena, 
about  three  feet.  On  the 
other  hand,  between  the 
converging  shores  of 
narrow  seas  and  bays 
the  water  is  sometimes 
heaped  up  to  the  height 
of  from  twenty-five  to 
forty,  and  in  the  Bay  of 
Fundy  from  fifty  to  sev- 
enty feet. 

The  Mediterranean  and  the 
Red  Seas,  however,  with  their 
narrow  and  shallow  entrances,  almost  cut  off  the  tidal-wave 
of  the  ocean,  so  that  neither  in  the  eastern  part  of  the 
Mediterranean,  nor  at  the  head  of  the  Red  Sea,  is  there  any 
regular  ebb  and  flow  of  tides . 

In  the  Caribbean  Sea  and  Gulf  of  Mexico,  likewise,  the 
tides  are  quite  feeble,  owing  probably  to  the  fact  that  these 
sheets  of  water  are  protected  from  the  tidal-wave  by  the 
West  Indies. 

Differences  on  the  same  Coast. — ^Very  great 
differences  exist  between  the  tides  at  various  points 
of  the  same  coast.     On  the  shores  of  Florida  the 


+  k 


N* 


k. 


N-v 


ATLANTIC    COAST    TIDES. 

(Mean  height,  in  feet.) 


6o 


WAVES   AND    TIDES. 


rise  is  not  more  than  about  three  feet.  It  increases  as 
we  go  northward,  until  we  reach  the  Bay  of  Fundy, 
wliere  it  attains  its  maximum.    [Sec  Chart,  p.  58.] 

At  some  points  on  tlie  shores  of  Great  Britain 
there  are  tides  of  great  hciglit  and  strength,  while 
at  others  close  by  tlie  rise  and  fall  are  barely  per- 
ceptible. 

The  rise  and  fall  at  Livcr[)Ool  are  28  feet  ;  in  the 
Bristol  Cliannel,  40  feet ;  at  Wieklow,  on  the  oppo- 
site Irish  coast,  only  two  or  three. 

Causes. — To  account  for  the&e  differences  various 
causes  may  be  suggested  :  tlie  form  of  the  bottom, 
the  projection  of   headlands,   tlie   narrowing  of 


THE   *'  BORE "   OF    THE    TSIEN-TSANO    KTVER. 


ordinary  velocity.  People  crossing  tlie  dry  bed  of 
the  river  Dee,  in  England,  are  often  overtaken 
and  drowned  by  the  inrush ing  water. 

The  case  of  the  Amazon  is  of  special  interest. 

The  tides  ascend  this  livcr  to  a  greater  distance  from  the 
sea  than  any  other  in  the  world.  Tide-water  extends  in  it 
700  miles  up  the  current ;  and  the  singular  phenomenon  is 
presented  of  there  being  several  tides  (Sir  John  Ilerseliel  says 
eight  *)  in  the  river  at  the  same  time;  for  before  the  flood 
of  one  has  reached  the  end  of  its  700  miles'  journey,  several 
other  tidal  waves,  each  in  succession  bringing  high  tide  with 
it,  have  had  time  to  enter. 

Bores. — A  tidal-wave  of  great  height  sometimes 
enters  the  mouth  of  a  river 
ind  ascends  its  channel 
as  a  perpendicular  wall 
of  water.  Such  a  tidal- 
wave  is  known  as  a  bore. 
Among  the  most  remark- 
able are  those  of  the 
Ilooghly  at  Calcutta,  tlie 
Garonne  in  France,  the 
Tsien-tsang  in  China, 
and  the  Amazon. 

At  certain  times  bores  13 
to  15  feet  high  come  rushing 
into  the  channel  of  the  Am- 
azon on  the  top  of  the  tide. 
Sometimes  as  many  as  five, 
:)0  or  40  miles  apart,  dash  up 
the  river,  capsizing  small 
craft  as  they  go  and  spread- 
ing consternation  among  the 
watermen. 

The  bore  of  the  Tsien-tsang 
is  even  greater  than  that  ot 
the  Amazon.  It  spans  the 
river  with  a  feather-wliite  and 
roaring  wall  of  water,  30  feet 
high,  and  travels  at  the  rate 
of  35  miles  an  hour. 


channels  along  wliich  the  tidal  current  is  forced, 
and  the  position  of  those  channels  with  reference 
to  the  direction  of  the  tidal  wave. 

A  glance  at  the  map  shows,  for  example,  that 
were  the  tidal-wave  propagated  from  the  northeast 
instead  of  tlie  southwest,  the  Bay  of  Fundy  would 
cease  to  be  celebrated  for  the  height  of  its  tides. 

The  peculiarities  of  a  shore  are  sometimes  such  as  to  cause 
a  complete  sundering  or  division  of  the  tidal  waters.  Two 
currents  are  thus  formed.  In  some  cases  these  meet  again 
after  their  division  and  give  rise  to  a  vJt  >  rljjOoL  Charybdis 
in  the  Straits  of  Messina,  and  the  Maelstrom  among  the 
Lofoden  Isles,  are  illustrations  of  this  phenomenon. 

.'>.  Tides  of  Rivers. — The  tide.-;  of  some 
rivers  iirescnt  intcresling  peculiariticsr 

Tliev  enter  certain  river  channels  with  extra- 


TOPICAL  ANALYSIS. 


Vn.    WAVES  AND  TIDES. 


1.    Waves. 


2. 


Uow  caused.  Crest  of  the  wave.  Breadth.  Nature 
of  wavc-motiou.  Height  and  velocity  of  ocean 
waves,  circumstances  affecting  velocity.  Efifect 
of  wave-movements.    Depth  to  which  the  motion 

(.■XtCIlcl^. 

Force  and  Work  of  the  Waves. 

Force  per  square  foot.  Effect  in  pulverizing  rocks. 
Ill  causing  encioaehmcnt  of  sea  lands. 


3.    The  Tides. 


General  description.     Origin  of  ilie  name.    Flood 
and  ebb  tides. 


*  "Physical  Geography,"  by  Sir  John  HerscheL 


CURRENTS    OF   THE    SEA. 


6i 


4.  Theory  of  Tides. 

Cuuse  of  high  tlik'S.  Low  tidus.  Evicloiice.  Spring 
and  noap  tides. 

5.  Origin  of  Tidal- Wave. 

6.  Movement  of  Tidal-Wave. 

Co-tidal  lines.  Curving  of  tlio  lines,  how  caused. 
Movement  of  the  wave  in  tlie  Pacific.  In  the 
Indian  Ocean.    In  the  Atlantic. 

7.  Speed  of  Tidal-Wave. 

Of  the  current. 

8.  Height  of  Tides. 

Cause  of  feeble  tides  in  certain  waters.  Difference 
in  tides  on  the  same  coast.    Causes.    Whirliiools. 

9.  Tides  of  Eivers. 

Tides  of  the  Dee.    The  Amazon.    Bores. 

Test  QtTESTioNS.— How  Is  the  expression  "waves  ninning  mountains 
high"  to  l)c  regarded?  What  is  tlie  general  effect  of  wave-action  along 
the  coasts  on  the  relative  area  of  land  and  sea?  Why  do  the  tides  occur 
a  little  later  every  day? 


VIII.  CURRENTS  OF  THE  SEA. 

1.  TJie  Currents  of  the  Sea, — There  are 
rivers  in  the  sea.  They  are  of  such  magnitude 
that  the  mightiest  streams  of  the  land  are  rivulets 
compared  to  them.  They  are  either  of  warm  or 
cold  water,  while  their  banks  and  beds  are  water 
of  the  02iposite  temf)erature.  For  thousands  of 
miles  they  move  through  their  liquid  channels  un- 
mixed with  the  confining  waters.  They  are  the 
horizontal  movements  called  currents. 

The  mariner  can  sometimes  detect  them  by  the 
different  color  of  their  stream,  while,  if  they  give 
no  such  visible  sign  of  their  existence,  he  can  trace 
them  by  testing  their  temjterature  with  his  ther- 
mometer. 

Classification. — The  chart  on  pages  62  and  6.3 
exhibits  a  general  view  of  the  oceanic  currents.  It 
presents  these  facts  : 

(1)  there  is  an  equatorial  current  sweeping  from 
east  to  west  all  along  on  either  side  of  the  equa- 
tor, and  well  nigh  encircling  the  globe  ; 

(2)  there  are  polar  currents  setting  from  the 
polar  regions  toward  the  equator  ; 

(3)  there  are  counter  currents  setting  from  the 
equator  toward  the  j^oles. 

Courses  of  Currents  Modified. — The  chart 
Bhows  that  as  in  the  case  of  the  tidal-wave,  so  in 
the  case  of  oceanic  currents,  the  shores  of  conti- 
nents and  islands  have  marked  efEeet  in  modifying 
their  normal  courses.  These  are  also  modified  by 
the  rotation  of  the  earth. 

Effect  of  Rotation. — Let  us  see  what  the  effect  of  rotation 
is.  If  two  trains  are  moving  on  parallel  tracks  in  tlie  same 
direction  and  with  the  same  speed,  an  object  thrown  or  a 
ball  shot  "  point  blank  "  from  one  to  the  other  may  strike 
the  point  aimed  at.     But  if  the  train  from  which  the  ball  is 


shot  be  going  3-5  miles  an  hour,  and  the  other  onlj  1.5,  the 

ball  from  the  first  will  strike  in  advance  of  the  point  aimed 
at.  If  the  direction  of  the  trains  be  eastward,  then  tlie  ball 
will  fall  a  certain  distance  to  the  east  of  the  slower  train. 

This  is  what  occurs  when  water  starts  from  the  eijuator 
toward  the  polos.  It  rotates  toward  the  east  at  the  sptiedof 
1,000  miles  an  honr.  Passing  to  either  pole  it  is  at  the  same 
time  moving  with  a  higher  speed  of  rotation  than  belongs  to 
the  latitudes  which  it  reaches,  and  hence  it  has  an  eastward 
movement. 

If  now  we  suppose  the  ball  to  be  discharged  from  the 
slower  train,  it  will  obviously  fall  behind,  or  to  the  westward 
of  the  point  aimed  at.  This  is  what  occurs  when  water 
starts  from  either  pole  to  the  equator.  It  has  the  slower  ro- 
tary motion  of  the  pole,  and  as  it  approaches  the  equator  it 
constantly  enters  latitudes  which  have  a  higher  speed  of 
rotation.  They,  as  it  were,  pass  it  by,  and  it  lags  to  the 
westward. 

Hence  currents  moving  to  the  poles  derive  from  rotation  an 
eastward  trend  ;  those  moving  to  the  equator  a  westward. 

Note.' — In  treating  of  oceanic  currents  it  is  important  to  ob- 
serve the  method  of  naming  thoni.  A  northeast  wind  comex 
from  the  northeast,  a  northeast  current  gocK  toward  the  north. 
east.  In  other  words,  while  the  winds  are  named  according  to 
the  points  from  which  they  blow,  currents  are  named  accord- 
ing to  the  quarter  toward  which  they  flow. 

2.  Currents  of  the  Atlantic. — We  will 
now  consider  the  currents  as  they  present  them- 
selves in  the  several  oceans.  For  convenience  we 
begin  with  the  Atlantic. 

The  Equatorial  Current  crossing  this  ocean 
between  the  shores  of  Africa  and  South  America 
strikes  the  latter  continent  at  Cape  St.  Roque. 
Here  it  divides.  One  portion  passes  southward, 
following  the  coast  line  of  South  America.  It  is 
named  the  Brazil  Current.  Its  waters,  reaching 
the  Antarctic  regions,  are  carried  back  with  the 
return  polar  current  which  sets  along  the  west 
coast  of  Africa  toward  the  equator. 

The  other  portion  of  the  Equatorial  Current,  on 
leaving  Cape  St.  Roque,  flows  northwestuiirdly. 
It  is  divided  by  the  West  Indies.  Its  main  section 
enters  the  Caribbean  Sea  and  the  Gulf  of  Mexico, 
from  which  it  issues  through  the  Straits  of  Florida 
as  the  well-known  Gulf  Stream. 

The  Gulf  Stream.— Among  the  counter  cur- 
rents which  carry  the  ocean  waters  from  the  equa- 
tor to  the  poles,  the  Gulf  Stream  is  the  most  re- 
markable. Issuing  from  the  Gulf  this  ocean  river 
crosses  the  Atlantic  in  a  northeasterly  direction. 
On  leaving  the  Straits  of  Florida,  it  takes  a  course 
nearly  parallel  to  our  Atlantic  seaboard.  Reaching 
the  latitude  of  Newfoundland,  it  turns  more 
directly  eastward. 

North  of  the  Azores  it  divides.  One  branch 
passes  southward,  skirts  the  western  shores  of 
southern  E^fcpe  and  Africa,  and  finds  its  way 
back  into  the  Equatorial  Current.  The  other 
branch  jiasses  on  to  the  northeast,  bathes  the  shores 


(Questions  on  the  Currents  op  th?  Sea. 

Atlantic  Ocean. — What  two  currents  carry  the 
Arctio  waters  into  the  Atlantic  ?  Trace  the  course  of 
the  Etiuatorial  Current  in  this  ocean.  <J5V^hat  does  it  be- 
come east  of  tlie  United  States  ?  Describe  the  course  of 
the  Gulf  Stream. 


What  current  bathes  the  southeastern  shores  of  South 
America?  Where  does  it  originate  ?  Into  what  ocean 
does  it  pass  ?  What  current  brings  into  the  Atlantic  the 
water  of  the  Antarctic  ?  Name  the  warm  currents  of  the 
Atlantic.     The  cold  currents.  ^^' 

Pacific  Ocean. — What  two  currents  form  the  Equa- 
torial Current  of  the  Pacific  ?    Where  do  they  blend  ? 


tii^Jk  V-,i,vVi.^'.?*x„.n.^X 


escribe  the  course  of  the  Equatorial  Current  ?    Where     I         Indian  Ocean.- Where  do  the  two  currents  that 


)es  it  divide  ?  Name  of  the  southern  branch  ?  Of  the 
)rthem  ?  Trace  the  Japan  Current.  What  name  has 
in  its  eastern  half  ?  Would  the  current  west  of  South 
merica  make  the  neighboring  shores  warmer  or  cooler? 
bj  1  Show  how  the  Pacific  system  of  currents  resem- 
■s  that  of  the  Atlantic. 


enter  the  Indian  Ocean  come  from  ?  What  current  issues 
from  this  ocean ?    What  is  its  course? 

Where  do  you  find  the  Sargasso  Seas  ?    How  many  ? 

Examine  carefully  the  drainage  of  each  continent  and 
tell  into  what  ocean  it  passes.  How  is  this  indicated  on 
the  chart  ?    What  regions  have  no  ocean  drainage  ? 


64 


CURRENTS   OF   THE    SEA. 


of  the  British  Isles  and  northern  Europe,  and 
enters  the  Arctic  basin,  possibly  to  emerge  through 
Bcliring  Strait  into  the  Pacific. 

Dimensions. — The  length  of  tlie  Gulf  Stream, 
from  the  Gulf  to  the  Azores,  is  about  3,000  miles. 
Its  breadth  in  the  Straits  of  Florida  is  about  32 
miles.  In  its  progress  it  constantly  increases  in 
breadth,  till  in  the  middle  of  the  Atlantic  it  is  120 
miles  across.  The  depth  is  about  2,400  feet  near 
the  straits.  This  naturally  diminishes  as  the  width 
Increases.  Oif  Charleston  it  is  reduced  to  1,800 
feet. 

In  volume  the  Gulf  Stream  exceeds  the  Missis- 
siijpi  more  than  1,000  times. 

Tlie  temperature  of  the  surface  waters  of  the 
Gulf  Stream,  as  they  pass  tlie  Straits  of  Florida, 
is  sometimes  as  high  as  85°  Fahr.  It  is  a  river  of 
warm  water,  and  retains  its  warmth  in  a  remarka- 
ble manner.  Off  Cape  Hatteras,  and  even  as  far 
as  the  Grand  Banks,  its  temperature  is  \b\  20°  or 
even  30°  higher  than  that  of  the  atmosphere. 

Tlie  storing  up  of  heat  begins,  no  doubt,  while 
the  Gulf  Stream  is  a  part  of  the  Equatorial  Cur- 
rent, and  continues  all  the  time  that  its  waters  are 
exjiosed  to  the  tropical  sun,  whether  in  the  Atlan- 
tic, the  Caribbean  Sea,  or  the  Gulf  of  Mexico. 

Color. — From  the  Gulf  up  to  the  Carolina 
coasts  the  waters  of  the  Gulf  Stream  are  of  an 
indigo  blue  ;  and  the  line  which  marks  the  di- 
vision between  them  and  the  edge  of  the  inshore 
■i\aters  is  sometimes  so  sharp  that  you  can  dis- 
tinguish when  one-half  the  vessel  is  in  the  Gulf 
Stream  and  the  other  is  in  the  cool  littoral  waters. 
The  line  of  demarcation  is  so  well-defined  that 
navigators  in  the  olden  times,  when  both  instru- 
ments and  methods  for  determining  longitude  at 
sea  were  rude,  used  to  Judge  by  it  of  their 
longitude. 

Offices. — The  offices  of  the  Gulf  Stream  are  two  : 
(1)  it  can-ies  the  warm  waters  of  the  torrid  zone 
into  the  Arctic  Ocean  ;  (2)  it  is  the  great  heat- 
earner  of  the  North  Atlantic  Ocean. 

Such  immense  volumes  of  heat  are  conveyed  by 
this  benignant  stream  to  northern  latitudes,  that 
the  winter  climate  of  the  whole  western  face  of 
Europe,  as  far  north  as  Lapland,  is  softened  and 
tempered  with  genial  warmth. 

The  ponds  of  the  Orkney  Isles,  though  bordering 
on  the  parallel  of  60°  north,  owing  to  this  mod- 
erating influence,  never  freeze  ;  and  the  harbor  of 
Hammerfesc,  m  latitude  70°  40',  the  most  nor- 
therly seaport  in  the  world,  is  always  open. 

Polar  Currents. — On  either  side  of  Green- 
land cold,  ice-bearing  currents  come  down  from 
the  Arctic  Ocean  to  replace  the  warm  water 
carried  northward  by  the   Gulf  Stream.     Off  the 


southern  point  of  Greenland  these  currents  unite 
and  advance  as  far  as  the  Grand  Banks. 

Here  one  portion  of  tiie  united  stream  sinks 
below  the  warmer  and  lighter  waters  of  the  Gulf 
Stream,  and  pursues  its  course  to  the  tropics  as  an 
undercurrent.  The  other  portion  turns  southwest 
and  follows  closely  the  eastern  coast  of  Nortli 
America,  keeping  between  the  shores  and  the  Gulf 
Stream,  as  far  south  as  Cape  Hatteras,  where  it 
passes  under  the  Gulf  Stream  and  continues  its  way 
toward  the  equatorial  regions  as  an  undercurrent. 


JilHTUrLACE  OF   lUE   ABCTIC  ICEEEKGS. 

This  current  supplies  the  markets  of  New  Eng- 
land with  the  choicest  fish  of  the  sea,  and  gives  to 
the  coast  of  Maine  its  singularly  cool  summer 
temperature. 

At  the  Grand  Banks  the  Arctic  Current  meets  the  Gulf 
Stream,  and,  cliilling  the  vapor  which  rises  from  its  surface, 
produces  the  ilense  fogs  which  render  this  part  of  the  ocean 
so  dangerous  to  navigation.     (See  p.  87.) 

From  the  Antarctic,  as  from  the  Arctic  Ocean, 
there  is  a  constant  flow  of  icy  waters  into  the 
Atlantic  basin.  The  South  Atlantic  Current, 
issuing  from  the  Antarctic  Ocean,  follows  the 
western  shore  of  Africa,  passes  northwestwardly, 
and  contiibutes  to  form  the  Ecpiatorial  Current  of 
the  Atlantic. 

^  3.  Currents    of   the  Pacific — Turning 
now  to  the  Pacific,  we  find  its  currents  presenting 


CURRENTS    OF    THE    SEA. 


65 


ill   general   similar  features  to  those  of  the  At- 
lantic. 

An  Equatorial  Current  starts  ■westward 
from  that  jiortion  of  the  ocean  lying  to  the  south- 
west of  Mexico.  Like  the  corresijonding  current 
of  the  Atlantic  it  divides.  One  branch  passes  to 
tlie  soutliward.  Bathing  the  shores  of  Australia, 
it  is  called  the  Australian  Current.  It  loses  itself 
in  the  Antarctic  waters. 

The  northern  branch  of  the  Equatorial  Current 
pursues  a  course  not  unlike  that  of  the  northern 
branch  of  the  Equatorial  Current  of  the  Atlantic. 
Passing  through  the  Archipelago  off  the  south- 
eastern coast  of  Asia,  it  turns  northward  and 
eastward,  and,  sweeping  past  the  Japanese  Islands, 
receives  from  them  its  name,  Japan  Current. 
The  natives  of  Japan  call  it,  from  the  darlc  blue 
color  of  its  waters,  Kuro  Si  wo,  i.e..  Black  Stream. 

The  Japan  Current  is  the  Gulf  Stream  of  the 
Pacific.  Like  that  stream,  it  has  the  twofold 
office  of  water-carrier  and  heat-bearer.  It  transfers 
the  water  of  the  central  and  western  Pacific  to  its 
northern  and  eastern  portions  ;  and  with  its  warm 
waters  it  softens  the  climate  of  the  Aleutian 
Islands,  and  the  northwest  coast  of  America,  just 
as  the  Gulf  Stream  does  the  climate  of  western 
Europe  and  the  British  Isles. 

Passing  the  Aleutian  Islands  the  main  volume  of  the 
Japan  Current  receives  the  name  of  the  Aleutian  Current, 
takes  a  southeastwardly  course,  and  becomes  again  a  portion 
of  the  Equatorial  Current. 

A  small  branch  of  the  Japan  Current  enters  the  Arctic 
Ocean  through  Behring  Strait. 

Polar  Currents. — A  small  surface  current 
issues  from  the  Arctic  Ocean  through  Behring 
Strait.  It  flows  between  the  Japan  Current  and 
the  eastern  shores  of  Asia,  like  the  polar  current 
which  flows  between  the  Gulf  Stream  and  the 
shores  of  America,  and,  like  the  corresponding 
current  of  the  Atlantic,  it  teems  with  excellent 
fish,  whereby  the  capacity  of  China  and  Japan  to 
sustain  population  is  greatly  increased.  It  brings 
down  field-ice  from  the  seas  of  Okhotsk  and 
Behring. 

From  the  Antai'ctic  a  broad  Drift  flows  toward 
the  equator.  Off  Cape  Horn  it  divides.  One 
branch  passes  into  the  South  Atlantic  ;  the  other, 
known  as  the  Humioldt  Current,  enters  the  Pacific. 

The  Humboldt  Current  carries  its  cool  Antarctic 
waters  all  along  the  west  coast  of  South  America 
from  Patagonia  to  the  Galapagos  Islands.  These 
waters,  when  they  touch  the  equator,  are  stiU  too 
cold  for  the  coral  insects  to  inhabit.  Hence  the 
whole  western  coast  of  South  America  is  without 
coral  reefs  or  coral  formations  of  any  kind  ;  though 
in  the  same  latitudes,  at  a  distance  from  the  coast. 


where  the  waters  are  warm,  the  ocean  is  alive  with 
them. 

After  crossing  the  equator  the  Humboldt  Cur- 
rent is  deflected  to  the  westward  and  becomes  part 
of  the  Equatoi'ial  Current  of  the  Pacific. 

4.  Curretitu  of  the  Indian  Ocean. — 

The  Indian  Ocean  has  no  such  well-defined  system 
of  cuiTeuts  as  the  Atlantic  and  Pacific.  A  branch 
of  the  Equatorial  Current  of  the  Pacific,  sweeping 
to  the  westward,  enters  this  ocean,  and  washes  the 
soutliern  shores  of  Asia.  Passing  Cape  Comorin 
it  is  deflected  to  the  south-west,  and  flows  along  the 
eastern  coast  of  Africa  as  the  Mozambique  Current. 
This  is  a  warm  current.  It  is  sharp  and  well-de- 
fined until  it  clears  the  Mozambique  Channel,  when, 
passing  southward,  it  loses  itself  in  the  Antarctic 
waters. 

From  the  Antarctic  a  cuiTent  setting  north- 
westward passes  to  the  soutliward  of  Australia  and 
pours  its  icy  flow  into  the  Indian  Ocean. 

o.  Oceanic  Circulation. — From  this  gen- 
eral survey  of  the  currents  of  the  sea  it  appears 
that  there  is  a  complete  system  of  circulation  hy 
which  thewaters  of  the  equatorial  and  polar  regions 
are  incessantly  changing  place  and  blending  to- 
gether. 

6.  Can-fes  of   Oceanic  Circnlatioti. — 

Two  main  causes  of  oceanic  circulation  have  been 
suggested.  They  are  (1)  difference  of  specific 
gravity  *  in  the  waters  of  various  j^arts  of  the  ocean; 
(2)  the  influence  of  the  winds. 

Difference  of  Specific  Gravity  between  sea 
water  at  one  place  and  sea  water  at  another  is  the 
chief  c-Mise  of  oceanic  circulation. 

Whenever  and  wherever  the  waters  in  one  part 
of  the  sea  differ  in  specific  gravity  from  the  waters 
in  another  part,  no  matter  from  what  cause  this 
difference  may  arise,  or  how  great  may  be  the  dis- 
tance between  two  such  parts  of  the  sea,  the  heavier 
water  will  flow,  by  the  shortest  and  easiest  route, 
toward  the  lighter ;  and  the  lighter,  in  its  turn, 
will  seek  the  place  whence  the  heavier  came. 

In  other  words,  fi-om  whatever  part  of  the  sea  a 
current  runs,  back  to  that  part  a  current  of  equal 
volume  must  flow. 

Changes  in  Specific  Gravity  are  mainly 
brought  about  by  (1)  heat  and  cold  ;  (2)  evajjo- 
ration  and  precipitation.  .--^c^ 

Effects   of  Heat  and    Cold. — Sea-water    when 


*  Two  bodies  are  said  to  differ  in  specific  gra\ity  when  equal  volumes 
or  measures  of  the  two  differ  in  weight.  A  gallon  of  salt  water,  for 
example,  weighs  more  than  a  gallon  of  fresh  water.  A  pint  of  water 
weighs  about  a  pound  ;  a  pint  of  quiclieilver  weighs  about  thirteen 
pounds. 


66 


CURRENTS    OF    THE    SEA. 


heated  expands.  A  given  volume  of  such  heated 
water,  if  it  contain  the  same  proportion  of  salts  as 
an  equal  volume  of  colder  salt-water,  will  weigh 
less.  On  the  other  hand,  when  sea-water  is  chilled, 
it  contracts  and  becomes  heavier. 

The  average  temperature  of  sea-water  is  for 
polar  seas  about  30°,  for  equatorial  aboiit  70°.  This 
diilercnce  of  temperature  is  permanent,  and  the 
diffei-encc  in  specific  gr-avity  of  sea-water  at  30°, 
and  sea-water  at  70°,  is  very  great. 

Tlie  colli  of  the  polar  regions,  therefore,  and  the  heat  of 
the  tropics  are  two  powerful  anil  ever-acting  causes  which 
]:roduce  constant  disturbance  of  equilibrium  in  the  waters 
of  the  ocean.  Necessarily  there  will  result  from  this  dis- 
turbance a  never-ceasing  movement  of  the  cold  waters  toward 
the  warm,  and  of  the  warm  toward  the  cold. 

\l  Effect  of  Evaporation. — If  you  evaporate  a  quan- 
tity of  sea-water  completely,  you  have  solid  saline 
matter  rcmaiiung.  In  proportion  therefore  to  the 
anTount  of  evaporation  going  on  upon  its  surface, 
a  body  of  sea-water  will  be  more  or  less  dense,  and 
consequently  more  or  less  heavy. 

Effect  of  rrecipitation. — Precipitation,  or  the 
process  by  which  moisture  is  returned  to  the  earth 
in  the  shape  of  rain,  snow  or  hail,  also  changes  the 
specific  gravity  of  sea-water. 

If  upon  any  jmrt  of  the  ocean  a  large  amount  of 
rain  falls,  or  if  rivers  flow  into  it,  the  sea-water 
becomes  less  salt  and  therefore  lighter. 

Illustrations. — Striking  illustrations  of  the  effect  of 
evaporation  and  precipitation  in  producing  currents  are 
furnished  by  the  Red,  Mediterranean  and  Baltic  Seas. 

The  Red  Sea  lies  under  a  burning  sun.  It  is  riverless  and 
almost  rainless,  while  the  evaporation  from  it  is  enormous. 
To  supply  the  waste  created  thereby,  a  constant  current 
from  the  Indian  Ocean  is  drawn  into  it  through  the  Straits 
of  Babelmandeb. 

In  the  Mediterranean  also  evaporation  is  very  great.  Into 
this  sea  rains  fall  and  rivers  flow.  Nevertheless,  the  sup- 
ply from  them  is  not  sufficient  to  make  up  for  the  loss  by 
evaporation.  The  deficiency,  therefore,  comes  in  through  the 
Straits  of  Gibraltar  as  a  surface-current  from  the  Atlantic. 

Tlie  water  of  these  two  seas,  after  it  has  supplied  the 
winds  with  vapor,  becomes  Salter  and  heavier  than  it  was 
before :  it  sinks  and  escapes  back  into  the  ocean  as  an  under- 
current. 

With  the  Baltic  the  case  is  reversed.  There  the  water 
which  is  received  from  the  rivers  and  the  rains,  is  more  than 
sufficient  to  balance  the  loss  by  evaporation.  Here,  there- 
fore, we  have  the  diluted  and  lighter  sea- water  escaping  from 
the  Baltic  as  a  surface- current,  while  an  undercurrent  of 
Salter  water  enters  from  the  North  Sea. 

We  can  now  appreciate  what  must  be  the  effect 
of  evaporation  and  precipitation  upon  the  general 
circulation  of  the  ocean. 

Between  the  equator  and  the  parallels  of  25° 
north  and  south  there  is  an  area  of  112,000,000 
square  miles.     Here  there  is  more  evaporation  than 


precipitation.  The  case  is  similar  to  that  of  the 
Bed  Sea. 

On  the  polar  side  of  latitude  50°  north  and  50° 
south  there  is  an  area  of  45,000,000  square  miles. 
Here  precipitation  is  in  excess  of  evaporation. 
The  case  is  parallel  to  that  of  the  Baltic. 

Now  try  to  estimate  the  total  quantity  of  water 
that  is  talien  up  by  evaporation  from  the  one  of 
these  f)arts  of  the  globe  and  poured  down  upon 
the  other,  and  the  disturbance  created  thereby  in 
the  equilibrimn  of  the  ocean. 

The  effort  to  restore  this  ecjiulibrium  is  seen  in  the 
currents  of  the  sea  and  the  circuTalTon  of  its  waters. 

A  more  accurate  measure  of  the  work  done  by 
evaporation  is  the  entire  annual  rainfall  upon  the 
surface  of  the  globe.  This  is  estimated  at  186,240 
cubic  miles,  or  more  than  510  cubic  miles  a  day. 
Eeflect,  then,  that  every  day  on  the  average  this 
immense  volume  of  water  is  being  ujilifted  by  the 
agency  of  evaporation  from  the  surface  of  the 
ocean,  and  you  will  be  better  able  to  estimate  the 
prodigious  influence  which  evaporation  must  exert 
in  disturbing  oceanic  equilibrium  and  j)roducing 
currents. 

7.  Salts. — The  solid  matter  of  sea-water  lends 
indispensable  aid  in  producing  the  currents  of  the 
ocean,  since  the  vast  and  ready  changes  of  specific 
gravity  upon  wliich  these  movements  depend  could 
not  occur  in  a  sea  of  fresh  water. 

For  if  two  portions  of  fre.sh  water  be  evaporated, 
one  more  than  the  other,  the  specific  gravity  of 
both  will  at  the  close  of  the  operation  be  the  same. 
But  mix  with  the  fresh  water  a  certain  amount  of 
common  salt ;  then  evaporate  one  portion  more 
than  the  other,  and  a  difference  in  the  specific 
gravity  of  the  two  portions  at  once  results. 

Just  so  any  diminution  of  or  addition  to  the 
saltness  of  any  portion  of  the  sea  produces  a  change 
in  its  specific  gravity  and  a  disturbance  of  its  equi- 
librium.    Hence  currents  result. 

And  thus  evaporation  really  owes  its  power  as  a 
cause  of  oceanic  circulation  to  the  salts  of  the  sea. 
The  very  separation  from  the  sea-water  of  solid 
matter  for  sea-shells  and  coral  reefs  is  a  continuous 
cause  of  difference  in  the  specific  gravity  of  the 
waters  of  the  ocean. 

It  seems  more  like  a  vagary  of  the  fancy  than  the  stub- 
bornness of  fact,  to  say,  that  so  great  a  matter  as  the  circu- 
lation of  the  water  in  the  sea  should  depend,  even  in  the 
slightest  degree,  upon  such  minute  creatures  as  the  little 
coral  reef-builder  and  his  tribe.  Yet,  look  at  the  great 
Barrier-reef  of  Australia,  the  coral  rocks,  reefs,  and  islands 
of  the  Pacific  Ocean.  Contemplate  the  quantity  of  matter 
which  is  required  to  build  these  structures,  and  say  if  the 
taking  of  it  out  of  solution  be  not  sufficient  to  disturb  the 
whole  ocean,  and  put  it  in  motion  from  the  equator  to  the 
poles. 


CURRENTS    OF    THE    SEA. 


67 


^   8.  Winds  a  Cause  of  Currents. — The 

Trade  Winds  are  considered  to  be  the  producing 
cause  of  the  Equatorial  Current  and  its  oH- 
slioots. 

Blowing  incessantly  to  the  westward  and  meet- 
ing over  the  equatorial  regions,  they  impart  to  the 
waters  beneath  them  a  gentle  but  continuous 
westerly  movement.  Hence  the  E(|uatorial  Cur- 
rent. 

Other  winds  produce  irregular  currents.  You 
may  yourselves  have  observed  the  effect  of  the 
wind  upon  rivers,  ponds,  or  canals,  in  piling  the 
water  up  on  one  side,  or  at  one  end,  and  blowing 
it  away  from  the  other. 

In  great  storms  at  sea  the  winds  drive  the  water 
before  them,  and  they  sometimes  pile  it  up  many 
feet  above  its  usual  level. 

Our  nautical  works  tell  us  of  a  storm  which  forced  the 
Gulf  Stream  back  into  the  Gulf,  and  piled  up  the  water  to 
the  lieight  of  30  feet.  The  Ledbury  attempted  to  riile  it 
out.  When  it  abated,  she  found  herself  high  up  on  dry 
land,  and  discovered  that  she  had  let  go  her  anchor  among 
the  tree-tops  on  Elliott's  Key. 

The  Florida  Keys  Were  inundated  many  feet,  and  it  is 
said  the  scene  presented  in  the  Gulf  Stream,  on  that  occa- 
sion, was  never  surpassed  in  awful  sublimity. 

The  water  dammed  up  rushed  out  with  wonderful  velocity 
against  the  fury  of  tlie  gale,  producing  a  sea  that  beggared 
description. 

9.  Office  of  Ocean  Currents. — The  great 
office  of  ocean  currents  in  general  is  to  modify  cli- 
mate. Those  from  equatorial  regions  are  carriers 
of  warmth  :  those  from  polar  regions  are  reducers 
of  heat. 


different  oceans  which  are  most  free  from  the  in- 
fluence of  currents. 

If  bits  of  eork  or  chips,  or  any  floating  substance, 
be  j3ut  into  a  basin,  and  a  circular  motion  bo  given 
to  the  water,  all  the  light  substances  will  be  found 
crowding  together  near  the  centre  of  the  pool 
where  there  is  the  least  motion.  Like  such  a  basin 
is  the  Atlantic  Ocean,  with  its  Equatorial  Current, 
and  its  Gulf  Stream.  The  Sargasso  Sea  is  the 
centre  of  the  whirl. 

The  Sargasso  Sea  of  the  Atlantic  embraces  an  area  of 
several  hundred  thousand  square  miles  ;  and  though  the 
weeds  are  all  afloat  and  held  by  nothing,  yet  the  Sargasso 
remains  where  it  was  nearly  400  years  ago,  when  Columbus 
passed  through  it  on  his  first  voyage  to  America. 

During  the  author's  researches  connected  with  the  ' '  Phys- 
ical Geography  of  the  Sea,"  the  existence  of  four  other 
Sargassos  was  established,  viz. :  one  in  the  Indian  Ocean, 
two  in  the  Pacific,  and  another  in  the  Atlantic.  [See 
Chart,  pp.  62,  63.] 


TOPICAL  ANALYSIS. 


l^ 


VIII.    CUKHENTS   OF   THE   SEA. 


GULF    WEED. 


10.  Sarffasso  Seas. — An  interesting  evidence 
of  the  circulation  of  the  oceanic  waters  is  to  be 
found  in  what  are  known  as  Sargasso  Seas,  so- 
called  from  sargazo,  the  Spanish  name  for  sea- 
weed. These  are  vast  collections  of  drifting 
eea-weed,  which  gather  in  those  portions  of  the 


1.  Currents  of  the  Sea. 

MagniUidc.  Temperature.  Cla.«sificati<ni.  Direc- 
tion, how  modified.  Trend  of  polar  and  counter 
currents.     Mode  of  naming  currents. 

2.  Currents  of  the  Atlantic. 

Tlie  Equatorial  Current.  Point  of  division.  Brazil 
Current.  The  Gulf  Stream.  Dimensions.  Tem- 
perature. Color.  OiEces.  Polar  currents,  north 
and  south. 

3.  Currents  of  the  Pacific. 

General  character.  Australian  Current.  KuroSiwo 
or  Black  Stream.  Polar  currents.  Humboldt  Cur- 
rent. 

4.  Currents  of  the  Indian  Ocean, 

5.  Oceanic  Circulation. 

6.  Causes  of  Oceanic  Circulation. 

Chief  cause.  General  law.  Causes  of  changes  in 
specific  gravity.  Effects  of  heat  and  cold.  Of 
evaporation.  Of  precipitation.  Illustrations  from 
the  Red,  Mediterranean  and  Baltic  Seas. 

^  7.    Effect  of  Salts  on  Circulation. 

Their  effect  in  promoting  changes  of  specific  grav- 
ity.   Effect  of  formation  of  coral-reefs. 

8.  Winds  a  Cause  of  Currents. 

Effect  of  Trade  Winds.    Of  storms. 

9.  Office  of  Ocean  Currents. 

10.  Sargasso  Seas. 

Description.    Cause. 


Niimher  and  location. 


Test  Questions. — Which  of  the  currents  of  the  sea  exerts  the  most 
important  influence  on  climate  ?  Why  ?  General  effect  ol  oceanic  cur- 
rents on  climate.  Effect  or.  saltness  of  the  sea.  Influence  on  com- 
merce. Are  the  currents  of  the  sea  of  any  benefit  to  marine  animals  ♦ 
Who  discovered  the  first  Sargasso  Sea  ? 


TOPICAL  ANALYSIS  F(m  REVIEW. 


Properties  of  Water. 


Composition. 

Changes  of  form.    Usee  in  Ihe  so/id  and  gaseous  forms. 

Expansion  in  freezing.    Iniporiant  resnit. 

Capacity  for  lieat  J    ''*''''  ■''■'"''■">''  latent  in  melting.    In  evaporation. 

1    EtTect  on  climate. 
Solvent  power. 
Circulation  between  sea  and  land. 


Waters  of  the  Land. 


Springs.     How  caused.    Reinarkaljle  kinds. 

Uow  formed,    liiver-systems.    Cataracts.    Offices  of  rivers. 


Rivera. 


Lakes. 


Uow  rivers  cliaugc  surface  of   tlie  earth. 


Erosion.    Cause.    Effects. 
Transportation 


Deposit  . 


Relation  to  ocean  life. 

Formation.    Cause  of  overflow.    Salt  lakes.    Inland  seas. 

Offices. 

Distribution. 


Power 

Quantity  of  matter. 

Causes. 


Results. 


Deflection  of  current 

Bars. 

Deltas. 

Branching  of  rivers. 


Drainage 


.Advantages. 
How  effected  . 


Quantity  of  water  delivered  by  rivers. 
Cause  of  inundations.    Examples. 


Continental  Drainage. 


North  America. 

South  America. 

Europe. 

Asia. 

Africa. 

Australia. 


The  Sea. 


Extent.    Relative  area  in  northern  and  southern  hemispheres. 

Saltness i     Saline  ingredients.    Quantity. 

'     Variation  with  distance  from  equator. 

Origin  of  saltness. 

Color. 

Phosphorescence. 

Temperature.    Variation  with  depth,  p?ace  and  season. 

Offices. 


The  Oceans. 


The  oceans 
Depth  .     . 

Bottom    . 


■1 


Number. 
Form  of  basin. 
The  Atlantic. 
The  Pacific. 


j     General  form. 

i     Beds  of  explored  oceans. 


Waves  and  Tides 


Ctirrents  of  the  Sea. 


Waves . 


Tides 


Currents  in  general  , 


Currents  of  tbe  Atlantic. 


Pacific  currents 

Currents  of  tbe  Indian  Ocean. 

Causes  of  oceanic  circulation. 
The  Sargasso  seas. 


How  caused. 

Nature  of  wave-motion.    Height.    Velocity. 

Force  and  work  of  waves. 

General  description. 

Theory  of  tides.    High.    Low.    Spring  and  neap. 

Origin  of  tidal  wave.    Movement  in  different  oceans.    Co-tidal  linee. 

Speed  of  tidal-wave. 

Height  of  tides  in  different  localities.    Cliarybdis  and  the  Maelstrom 

Tides  of  rivers.    Bores. 

Maonitnde.    Temperature.    Classification, 

Direction.    How  modified.    Rotation. 

Mode  of  naming. 

Equatorial  Current.    Brazil  Current. 

Gulf  Stream,     Polar  currents. 

General  character.    Australian  Current. 

Japan  Current.     Polar  currents. 

Chief  cause.     General  law. 

Causes  of  changes  in  specific  gravity. 

Effect  of  salts  on  circulation. 

Winds  a  cause  of  currents.    Office  of  ocean  currents. 


1 


PART      IV. 


THE    ATMOSPHERE, 


I.    PHYSICAL  PEOPERTIES    OF   THE 
ATMOSPHERE. 

1.  The  Atnioapliere. — Wherever  we  go  on 
the  surface  of  the  earth  we  perceive  that  air  is 
present.  If  we  ascend  above  the  mountain  tops, 
or  pierce  the  loftiest  clouds,  it  is  still  with  lis.  It 
envelops  the  earth. 

The  entire  mass  of  the  air  is  commonly  spoken 
of  as  the  atmosphere.  Its  upper  portion,  which  on 
a  clear  day  is  blue,  we  call  the  sky. 

Composition. — The  first  question  which  natu- 
rally occurs  to  us  regarding  the  air  is,  What  is  it  ? 
It  was  long  thought  to  he  an  element,  i.e.,  some- 
thing unmixed  with  anything  else.  About  one 
hundred  years  ago  it  was  found  to  consist  mainly 
of  two  gases.  Names  had  to  be  invented  for  them. 
They  were  called  Oxygen  and  Nitrogen.  In  every 
one  hundred  gallons  of  air  there  are  about  seventy- 
eight  of  nitrogen  and  about  twenty  of  oxygen. 
Vapor  of  water  and  carbonic  acid  gas  are  also  pres- 
ent in  the  atmosphere.  The  latter  consists  of 
carbon  combined  with  oxygen. 

The  vapor,  besides  its  other  offices,  mitigates  the  fierce- 
ness of  the  solar  rays  by  day,  and  prevents  radiation  into 
space,  or  the  escape  by  night  of  certain  portions  of  the  heat 
that  the  earth  receives  from  the  sun  during  the  day. 

The  plants,  by  means  of  their  leaves,  appropriate  carbon 
from  the  carbonic  acid.  From  it,  and  the  water  obtained 
through  their  roots,  they  elaborate  fibre,  fruits  and  flowers, 
returning  the  oxygen  again  to  the  air  for  the  use  of  '  ■  every- 
thing that  hath  breath." 

2.  Weight  of  the  Air. — As  we  do  not  feel 
ourselves  pressed  down  by  the  air,  it  may  seem 
surj^rising  that  it  has  weight.  Yet,  in  truth,  it  is 
very  heavy.  The  famous  Galileo  was  the  first  to 
point  this  out.  A  pump-maker  wished  to  know 
from  him  why  a  pump  would  not  raise  water  from 
a  well  which  was  more  than  thirty-two  feet  deep. 
Galileo  concluded  that  it  was  because  a  column  of 
water  thirty-two  feet  high  is  as  much  as  the  weight 
of  the  air  can  balance. 

Barometer. — Torricelli,  a  celebrated  pupil  of 
Galileo,   confirmed  the  conclusion  of  his  master. 


He  filled  a  tube,  about  three  feet  in  length,  with  mer- 
cury. He  then  inverted  the  tube  and  placed  the  open 
mouth  m  a  vessel  of  mercury.  The  mercury  in  the 
tube  then  fell,  until  ir  was  about  thirty  inches  in 
height.  This  column  of  mercury  was  sustained  by 
the  weight  of  the  air.  Torricelli  thus  discovered 
wbat  is  known  as  the  iarometer  or  weight-measure, 
(from  the  Greek  baros,  weight,  and  metron, 
measure). 


TORRICELLI'S   EXPERIMENT. 


BAROMETER. 


Pascal,  a  French  philosopher,  completed  the 
work  of  Galileo  and  Torricelli.  He  argued  that  if 
the  atmosphere  has  weight,  that  weight  must  be 
less  on  the  top  of  a  mountain  than  down  at  the 
base,  and  that,  consequently,  a  less  column  will  be 
sustained  above  than  below.  The  experiment  was 
tried  upon  the  Puy  de  Dome,  a  lofty  mountain  in 
France.  It  established  the  fact  that  the  air  has 
weight ;  for  the  mercury  fell  about 
every  ascent  of  about  ninety  feet. 


^\  inch  for 


70 


PHYSICAL  PROPERTIES  OF  THE  ATMOSPHERE. 


The  weight  of  the  atmosphere  is  commonly  called 
its  pressure. 

Amount  of  Pressure. — At  the  level  of  the 
sea  the  atmosphere  presses  with  the  weight  of 
fifteen  pounds*  upon  every  square  inch.  Although 
its  pressure  upon  the  body  of  each  one  of  us  is 
several  thousand  pounds,  yet,  in  consequence  of 
the  simple  law  of  nature,  that  tlie  atmosphere 
presses  equally  in  all  directions,  we  do  not  feel  it. 

An  interesting  consequence  of  the  weight  of  the  atmos- 
phere is  the  fact  that  the  boiling  point  is  lowered  at  high 
elevations.  At  about  the  level  of  the  sea,  water  boils  at 
212°  Fahr.  At  Quito,  11,000  feet  high,  the  boiling  point 
is  194°  Fahr.  On  the  top  of  Mont  Blanc,  nearly  16,000 
feet  high,  it  is  180". 

This  arises  from  the  diminished  pressure  to  which  water 
is  subjected  at  great  elevations.  It  has  the  inconvenient 
effect  of  making  it  impossible  in  such  situations  to  cook  by 
boiling.  y 

\j  Variations  in  Pressure. — Variations  in  at- 
mospheric pressure  are  occasioned  (1)  by  change  of 
level ;  (2)  by  changes  in  the  weight  of  the  air. 

Effect  of  Change  of  Level. — As  you  asoend 
a  mountain,  you  pass  through  a  certain  proportion 
of  the  atmosphere,  and  are,  of  course,  relieved 
from  a  portion  of  its  pressure.  For  the  first  10,000 
feet  of  ascent  the  barometer  falls  ten  inches  ;  an 
average  of  one  inch  to  every  1,000  feet  of  ascent. 
For  the  second  10,000  feet  the  barometer  would 
fall  about  6.7  inches,  the  amount  of  its  fall  con- 
stantly decreasing  as  you  ascend.  Mr.  Glaisher 
in  his  balloon  reached  a  height  of  37,000  feet, 
and  then  the  barometer  went  down  to  seven  inches. 

The  lowest  reading  of  the  barometer  ever  ob- 
served upon  a  mountain  was  13.3  inches,  at  an 
elevation  of  22,079  feet,  on  the  summit  of  Ibi- 
Gamin,  in  Thibet.  It  is  easy  to  see  that  the 
amount  of  fall  furnishes  a  means  of  measuring 
heights  of  mountains,  and  altitudes  to  which 
balloons  ascend. 

Effect  of  Changes  in  Weight  of  the  Atmos- 
phere.— A  fall  of  barometer  occurs,  also,  when 
the  column  of  air  above  any  area  becomes  lighter 
than  usual.  This  takes  place  when  there  is  more 
than  the  ordinary  amount  of  vapor  in  the  air ; 
because  vapor  is  lighter  than  dry  air.  Conse- 
quently, the  greater  the  proportion  of  vapor  in  the 
air,  the  lighter  that  air  will  be.  A  loiv  larometer 
therefore  usually  indicates  a  moist,  rainy  atmos- 
phere. A  high  larometer  indicates  that  the  atmos- 
phere is  heavy  ;  either  because  it  is  dry,  or  because 
it  is  dense. 

Height  of  Atmosphere. — The  main  body  of 


*  This  may  he  verified  by  the  simple  experiment  of  employing  a 
barometric  tulie  one  square  inch  in  bore.  A  column  of  mercury  thirty 
inches  high  in  ouch  a  tube  weighs  fifteen  poands. 


the  atmosphere  is  about  forty  miles  high.  It 
proljably  extends  in  a  state  of  extreme  attenuation 
to  the  height  of  several  hundred  miles. 

The  Density,  or  compactness  of  the  air,  of 
course  diminishes  with  tlie  height.  On  lofty 
mountains  it  is  highly  rarefied,  which  means  that 
its  particles,  being  relieved  from  pressure,  are 
more  widely  separated  from  one  another  than  at 
lower  levels. 

Persons  ascending  to  great  elevations  sometimes  expe- 
rience a  singular  difficulty.  The  walls  of  the  blood-vessels 
burst,  and  there  is  a  flow  of  blood  from  the  nose  and  ears. 
This  mal  de  montagne  is  seldom  felt  at  a  lower  level  than 
16,000  feet,  and  balloon  ascents  have  been  made  to  a  height 
of  29,000  feet  before  any  serious  inconvenience  has  arisen 
from  this  cause. 

TOPICAL    ANALYSIS. 
I.    PHYSICAL  PEOPERTIES  OF  THE   ATMOSPHERE. 

1.  The  Atmosphere. 

Composition.  Uses  of  llie  vapor  of  water  and  car- 
bonic acid. 

2.  Weight  of  the  Air. 

Evidence  that  the  air  has  weight  from  the  action  of 
the  common  pump.  From  Torricelli's  experiment. 
From  Pascal's  experiment. 

Amount  of  pressure.  Effect  of  presstire  on  the 
boiling  point.  Variations  in  pressnpe,  to  what 
due.  Effect  of  change  of  level.  Lowest  baromet- 
ric readings  observed.  Effect  of  change  in  the 
weight  of  the  air.  Meaning  of  high  and  low 
barometer.  Height  of  the  atmosphere.  Variation 
of  density  with  height.    Physiological  effect. 

Test  Qcestioss.— Wliat  is  the  color  of  the  atmosphere  ?  Of  what 
use  is  this  to  us  f  A  cubic  yard  of  air  weighs  about  2.2  lbs  ;  what  is  the 
weight  of  the  air  in  a  room  1.5  feet  square  and  12  feet  high  ?  Have  you 
ever  observed  anything  to  Indicate  that  the  air  has  weight  ?  How  long 
ago  did  Galileo  live  ?  Above  the  mercury  in  the  barometer  is  a 
vacant  space  called  the  Torricellian  vacuum  :  whv  should  it  be  so 
called  ? 

II.  CLIMATE. 

1,  Main  ElenientH. — The  temperature  and 
moisture  of  the  air  are  the  two  main  elements  of 
climate.  Obviously  the  more  important  of  these 
is  temperature. 

The  principal  causes  which  modify  temperature 
are,  distance  from  the  Equator  ;  distance  from  the 
sea ;  prevailing  winds  and  ocean  currents ;  and 
height  above  the  sea-level. 

2.  Distance  from   the  Equator. — The 

first  and  most  aj^pareut  cause  of  difference  of  cli- 
mate is  distance  from  the  Equator.  This  has  two 
results  :  (1)  as  the  distance  increases,  the  average 
annual  temperature  falls  ;  and  (2)  there  are  greater 
and  greater  contrasts  of  summer  heat  and  winter 
cold. 
Effect  on  Annual  Temperature. — The  area 


CLIMATE. 


71 


within  the  tropics  receives  the  vertical  rays  of  the 
sun,  and  is  therefore  tlic  region  of  greatest  lieat. 

Between  the  trojoics  and  the  pohir  circlcs^the 
sun's  rays  fall  slantingly,  and  exert  therefore  a 
feebler  power. 

Within  the  polar  circles  the  slant  of  the  sun's 
rays  is  at  its  greatest,  and  hence,  except  during  a 
brief  period  of  a  few  weeks,  excessive  cold  pre- 
vails. 

The  reason  why  less  heat  is  received  where  the  sun's  rays 
are  oblique  may  be  readily  understood  from  the  accompany- 
ing diagram. 

If  tlie  beam  of  heat,  HIT',  fall  vertically,  it  will  be  dis- 
tributed over  a  smaller  space  (CB)  than  if  it  falls  obliquely. 
The  amount  of  heat,  therefore,  received  at  any  iioiiit  along 


AB  is  diminished  in  the  same  ratio  as  the  surface  is  increased. 
The  intensity,  therefore,  of  tlie  heat  upon  the  surface  AB  is 
to  its  intensity  upon  CB,  inversely  as  the  surfaces,  or  as  CB 
is  to  AB. 

Climatic  Contrasts. — The  contrasts  between 
siunmer  heat  and  winter  cold  are  mainly  due  to 
variations  in  the  length  of  the  day,  and  these  de- 
pend on  distance  from  the  Equator. 

Within  the  trojjics  there  is  comparatively  little 
difference  between  the  two  periods  of  day  and 
niglit  all  through  the  year. 

Only  twice  in  the  year,  at  the  equinoxes,  are  they 
equal  for  other  parts  of  the  globe. 

As  the  sun  passes  northward  from  the  Equator, 
the  day  lengthens  all  over  the  northern  hemi- 
sphere, until,  within  the  Arctic  circle,  the  sun  does 
not  set  at  midsummer  at  all.  The  same  thing 
occurs  for  the  southern  hemisphere,  after  the  sun 
passes  southward  of  the  Equator. 

Now  it  is  because  there  is  very  little  difference 
between  day  and  night  at  the  Equator  that  we 
find  within  the  tropics  a  nearly  uniform  tempera- 
ture throughout  the  j'ear. 

And  it  is  because  north  and  south  of  the  tropics 
there  are  important  differences  between  day  and 
night,  that  in  all  regions  outside  of  the  tropics  cli- 
matic contrasts  are  found. 

At  the  poles  these  contrasts  are  at  their  maxi- 
mum. The  summer  of  the  polar  regions,  strange  to 
say,  is  exceedingly  hot.*  It  is  marked  by  a  ra- 
pidity of  vegetable  growth  that  is  marvellous.     In 


*  At  Yakutsk,  about  300  miles  south  of  the  Arctic  circle,  the  temjiera- 
turo  varies  from-fiS"  Fahr.  iu  winter  to  99°  in  summer. 


a  few  weeks  crops  mature  which  require  twice 
that  length  of  time  in  latitudes  much  nearer  the 
Equator.  But,  on  the  other  hand,  the  winter  cold 
is  correspondingly  excessive. 

Explanalion. — We  shall  better  understand  the  climatic 
effects  of  variations  in  the  length  of  day  and  night,  if  wo 
know  somelhitig  about  the  absorption  and  radiation  of  heat 

If  two  bodies  are  of  dilTerent  temperatures,  heat  wiU  pass 
through  the  space  between  them  from  the  warmer  to  the 
cooler.  The  giving  off  of  heat  by  the  warmer  body  is  called 
radiatiun.  The  receiving  of  it  by  the  cooler  is  called  06- 
sorption. 

If  a  red-hot  cannon-ball  be  placed  near  a  mass  of  ice,  heat 
will  be  radiated  from  the  cannon-ball  to  the  ice.  The  ice  will 
absorb  the  heat  from  the  ball.  So  wherever  the  sun  is  shin- 
ing, the  earth  is  absorbing  heat.  Wherever  it  is  night-time, 
the  earth  is  radiating  heat  into  the  cooler  regions  of  space. 

It  is  clear  that  when  the  day-time  of  northern  regions  is 
lengthened,  the  quantity  of  heat  absorbed  is  greater;  and, 
at  the  same  time,  since  the  nights  are  shorter,  the  loss  of 
heat  by  radiation  is  less.  Hence,  there  is  every  day  an  ac- 
cumulation of  heat. 

It  is  for  this  reason  that  our  own  hottest  weather  occurs 
subsequently  to  the  longest  day,  and  that  in  places  like  St. 
Petersburg  and  Yakutsk,  where  the  sun  is  below  the  hori- 
zon at  midsummer  only  for  about  three  hours,  the  summer 
heat  is  mtense. 

3.  Distance  from  the  Sea. — In  certain 
cbuntries  climate  is  affected  more  by  distance  from 
the  sea  than  by  distance  from  the  Equator. 

The  climate  of  a  region  adjacent  to  the  sea  is 
called  an  insular  or  maritime  climate.  The  cli- 
mate of  a  region  remote  from  the  sea  is  called  an 
inland  or  continental  climate. 

Insular  Climates. — Certain  causes  moderate 
insular  climates. 

(1)  Water  absorbs  heat  much  more  slowly  than 
the  laud,  and  therefore  remains,  in  hot  weather, 
comparatively  cooler.  Hence  the  summer  tempera- 
ture of  a  country  bordering  on  the  sea  is  lowered. 

(2)  On  the  other  hand,  water  parts  with  its  heat 
by  radiation  much  more  slowly  than  the  land,  and 
therefore  remains  in  cold  weather  comparatively 
warmer.  Hence  the  winter  of  a  maritime  country 
is  moderated. 

(3)  Vapor  is  incessantly  rising  from  the  sea,  and, 
being  condensed,  falls  as  rain  or  snow  upon  the 
land,  and,  as  you  have  learned,  this  liberates  latent 
heat. 

(4)  The  vapor  in  the  atmosphere  of  a  maritime 
climate  prevents  the  escape  of  heat.  It  acts  like  a 
warm  blanket.  A  familiar  illustration  of  this  is 
the  fact  that  we  rarely  have  frost  on  cloudy  nights. 

(5)  But  again,  since  the  process  of  evaporation 
goes  on  more  rapidly  in  hot  weather  than  in  cold, 
it  has  the  effect  of  moderating  the  summer  heat  of 
a  maritime  couotrv. 

For  the  above  reasons,  insular  or  maritime  cli- 
mates are  equable,  or  free  from  extremes. 


\i™*ixVv  ^,'««\\».'!i^ 


Questions  on  the  Isothermal  Chart. 

What  are  isothermal  lines  ?  Why  should  the  isotherms 
be  so  irregular  and  differ  so  much  from  the  parallels  of 
latitude  ? 

New  York  and  Rome  are  in  about  the  same  latitude ; 

how  do  Uieir  mean  temperatures  compare  ?    The  same 


isotherm  passes  near  New  York  and  London:  how  much 
difference  is  there  in  the  latitude  of  these  two  cities  ? 

Trace  the  course  of  the  Thermal  Equator.  What  is 
the  average  annual  temperature  of  places  tnrough 
which  it  passes  ?  What  isotherms  bound  the  zones  of 
Tropical  temperature  ?  What  isotherms  bound  the 
Temperate  zones  ?    The  Polar  ?    Through  what  coun- 


20  HO  10  r.o  eci  70  00  iH)  100  u<i  i2uLoTii/uaoh/dp   uoM'ojf f  tr,n//vm  umOnivintuvi'^  xho  no 


ISOTHERMAL  LINES] 


H  ZOtlESoFTEMPERATURl, 
^     1        i^-------i^-^-j- 


± 


m  107  ^  J17  127  137  M?  167  107  1?7  173  lGa/-flW,</a5aft/^fr    1*8  ITcrfiaS  J^W/ 123  W^wAai3l>);-/ft'7U' J 


J 


'fciiM^i,\)^ii5.«nuin\,S    :, 


.ties  of  each  continent  does  the  isotherm  of  33°  pass  ? 

North  of  this  line  what  is  the  condition  of  the  ground? 
n  which  continent  is  the  "limit  of  constantly  frozen 
rround"  farthest  to  the  north  ?  On  which  side  ot  ourcon- 
inent  is  it  farther  north  ?  What  difference  between  the 
nnual  temperature  of  Labrador  and  the  British  Isles  ? 

What  parts  of  North  and  South  America  have  the  same 


annual  temperature  as  Italy  and  Spain  ?  What  parts  of 
Europe  have  the  same  annual  temperature  as  Alaska  ? 

What  should  you  judge  from  the  chart  to  be  the  annual 
mean  temperature  of  Mobile  ?  Of  Rio  de  Janeiro  ?  Of  St. 
Louis  ?  Of  Charleston  ?  Of  Buenos  Ayres  ?  Of  Paris  ? 

Where  are  the  two  poles  of  greatest  cold  in  the  nor- 
thern hemisphere  ? 


74 


CLIMATE. 


Inland  Climates. — Inland  or  continental  cli- 
mates are  the  opposite  of  maritime.  They  are  sub- 
ject to  (/rent  extremes,  intense  heat  in  summer  and 
excessive  cold  in  winter. 

Two  reasons  may  bo  assigned  for  this: 

(1)  Countries  far  from  iiie  sea  are  without  its 
cooling  influence  upon  their  summer  heut,  and 
they  have  no  reservoir  of  warmth  to  compensate 
for  their  rajsid  radiation  of  heat  in  winter. 

The  interior  of  Asia  affords  tlie  most  striking  instances 
of  the  excessive  character  of  inland  climates.  The  Russian 
army  advancing  towards  Khiva  in  1839-40  experienced 
vicissitudes  of  temperature  from  a  heat  of  over  100°  Fahr. 
to  a  cold  of  45"  below  zero. 

At  Yakutsk,  in  Eastern  Siberia,  the  culminating  point  of 
excessive  climate  in  all  the  world  is  readied.  The  tempera- 
ture there  sinks  to  the  lowest  known  point,  many  degrees  be- 
low the  average  of  tlie  jiolar  ocean  to  the  northward  of  it, 
and  the  soil  is  permanently  frozen  to  the  depth  of  380  feet. 
In  the  month  of  June  the  Lena  is  free  from  ice;  the  surface 
soil  has  thawed  for  3  or  4  feet;  and  the  warmth  of  the 
short  summer  is  such  that  grain  will  ripen  in  the  shallow 
stratum  of  soil  above  the  frozen  mass.  The  mean  temjiera- 
ture  of  July  is  G9°  Pahr.,  or  as  high  as  that  of  Paris. 

(2)  The  comjiarative  dryness  of  the  air  of  an 
inland  region  contributes  to  create  extremes.  This 
is  strikingly  illustrated  by  the  climate  of  the  Sa- 
liara.  Tlie  air  there  is  jierfectly  dry.  No  vapor 
hinders  tlie  reception  of  heat  by  day  or  its  loss  by 
night.  By  day  the  sand  is  as  fire  and  the  wind 
like  flame  ;  and  yet  the  temperature  often  falls 
from  200°  Fahr.  during  the  day  to  freezing-point 
during  the  night. 

Travellers  have  been  known  to  find  the  water  in 
their  canteens  turned  into  ice  before  morning. 

4.  Pyei'ailiug  Winds  and  Ocean  Cuv- 

rents. — The  climate  of  a  country  is  also  greatly 
modified  by  the  prevailing  winds  and  the  neighbor- 
ing ocean  currents.  If  the  prevailing  winds  come 
from  the  sea,  they  temper  the  extremes  of  heat 
and  cold.  If  a  cold  current  bathes  any  portion  of 
the  shore,  it  lowers  the  temperature  ;  a  warm  cur- 
rent raises  it. 

Examples. — The  British  Isles  and  the  province 
of  Labrador  are  the  same  distance  from  the  Equa- 
tor, and  in  many  jiarts  the  same  height  above  the 
sea.  Yet  such  is  the  difference  of  climate  be- 
tween them,  that  Labrador  is  covered  with  snow 
for  nine  or  ten  months  every  year,  and  is  so  cold 
as  to  be  almost  uninhabitable  ;  while  in  England 
the  ground  is  rarely  covered  with  snow,  and  the 
jtastures  are  green  all  the  winter. 

Both  countries  ate  in  the  regions  of  westerly 
winds  ;  but  in  Labrador  they  come  from  the  land, 
and  arc  dry  and  cold  ;  in  England  they  come  from 
the  sea,  and  are  laden  with  moisture  and  warnith. 
The  shores  of  Labrador  are  washed  bv  a  cold  Arc- 


tic current ;  those  of  Great  Britain  by  the  warm 
waters  of  the  Gulf  Stream. 

The  climates  of  Western  Eurojie,  from  North 
Cape  all  the  way  down  to  the  Straits  of  Gibraltar, 
are  modified  by  the  sea-winds  and  the  influence  of 
the  Gulf  Stream. 

Norway  stretches  up  beyond  the  70th  degree  of  north  lati- 
tude ;  yet  the  westerly  winds  are  so  richly  laden  with 
warmth  and  moisture  from  the  waters  of  the  Gulf  Stream 
that  the  harbor  of  llammerfest,  lat.  70"40',  is  never  frozen, 
even  in  the  severest  winters.  But  cross  the  Scandinavian 
mountains,  and  you  encounter  at  once,  if  it  he  winter,  tho 
severest  cold.  In  this  short  distance  from  the  warm  waters 
and  the  west  winds  ot  the  Atlantic,  you  find  the  Russian 
lakes  and  rivers,  the  gulfs  and  bays  of  the  Baltic,  closed 
against  navigation  every  year  from  November  till  May. 

Climatic  conditions  similar  to  those  which  affect 
the  western  shores  of  Europe  are  found  upon  the 
western  slopes  of  Oregon,  British  Columbia,  and 
Alaska.  Westerly  winds  prevail,  and  they  are 
laden  with  moisture  from  the  Pacific  Ocean.  The 
result  is  that  here,  as  in  Norway,  open  harbors  and 
evergreen  hills  are  found  in  the  high  latitudes  of 
Alaska  and  other  parts  of  our  northwest  coast. 

i  5.  Height  above  the  Sea-Level. — Among 
other  circumstances,  climate  depends  upon  height 
above  the  sea.  A  change  of  elevation  of  a  few 
thousand  feet  at  the  Equator  produces  a  change  of 
temperature  as  great  as  would  be  experienced  in 
sailing  6,000  miles  to  the  frozen  regions  of  the 
poles.     [See  small  map  j).  105.] 

The  Island  of  Cuba  and  the  Mexican  mountain 
of  Orizaba  are  in  the  same  latitude.  The  summit 
of  the  mountain  is  covered  with  snow  all  the  year ; 
the  island  with  fruits,  flowers,  and  evergreens. 

The  reason  why  elevation  above  the  sea-level 
causes  reduction  of  temperature  is  that  the  radia- 
tion of  heat  goes  on  from  elevated  parts  of  the 
earth's  surface  more  freely  than  from  its  lower 
portions.  Two  causes  may  be  assigned  for  this : 
(1)  elevations  are  comparatively  small,  and  there- 
fore lose  heat  with  rapidity  ;  (2)  the  air  and 
vapor  upon  elevations  are  rarefied,  and  hence  little 
hindrance  to  radiation  is  presented. 

The  general  rule  as  to  the  effect  of  elevation  is 
this  :  for  every  one  hundred  yards  of  perpendicu- 
lar ascent  there  is  a  decrease  of  one  degree  in.  the 
temperature;  so  that,  even  at  the  Equator,  you 
may,  by  ascending  to  the  height  of  about  sixteen 
thousand  feet  above  the  sea,  reach  the  snow-line, 
where  the  cold  is  extreme  and  the  winter  eternal. 

~^(>.  Isothet-nial  Lines.— From  thcrmomet- 
ric  observations  made  in  all  parts  of  the  world,  the 
actual  distribution  of  temperature  over  the  globe 
has  been  ascertained.  To  show  this,  Humboldt 
constructed  a  series  of  lines  called  tsothermals  or 


WINDS  AND  CIRCULATION  OF  THE  AIR. 


75 


lines  of  equal  heat.  These  arc  drawn  round  the 
globe  so  as  to  connect  all  places  wliic^h  have  tlie 
same  mean  temperature  during  the  year  or  ajiy 
given  part  of  the  year. 

Isothermal  lines  are  far  from  coinciding  with 
the  parallels  of  latitude.  Let  us  take  by  way  of 
illustration  the  line  in  the  Northern  Hemisphere 
indicating  the  mean  annual  temperatute  of  50° 
Fahr.  [See  chart  pf).  73,  73.]  It  passes  through 
Oregon  on  the  Pacific  shores,  and  leaves  our 
Atlantic  coast  between  New  York  and  New 
Haven.  It  bends  northward  in  crossing  the  At- 
lantic, and  in  Europe  passes  through  Liverpool, 
Vienna,  and  Odessa,  and  in  Asia,  near  Peking. 

We  are  not  to  conclude,  however,  that  because 
the  same  isothermal  line  passes  through  two  places, 
they  have  a  climate  identically  the  same.  Of  two 
such  places  one  may  have  an  extremely  liot  sum- 
mer and  a  correspondingly  cold  winter.  The  other 
may  have  a  climate  free  from  extremes.  Yet  both 
may  have  tlie  same  average  yearly  temperature. 

Thus  San  Francisco  and  Washington  have  the  same 
mean  annual  temperature,  while  their  climates  are  very 
different. 

Again,  the  same  isothermal  line  passes  through  New 
York  and  Dublin.  Yet  the  climates  of  these  places  have 
no  resemblance.  The  mean  winter  temperature  of  Dublin 
is  six  degrees  above  that  of  New  York  ;  while  the  summers 
of  the  two  places  are  so  unlike,  that  whereas  grapes  and  In- 
dian corn  are  successfully  cultivated  in  the  vicinity  of  New 
York,  they  will  not  ripen  in  the  open  air,  at  Dublin. 

Zones  of  Temperature. — By  means  of  iso- 
therms we  define  the  zones  of  temjierature.  They 
are  indicated  by  the  colors  on  the  chart.  The  true 
Torrid  Zone  is  bounded  by  the  isotherms  of  70°  on 
either  side  of  the  Equator.  The  true  Temperate 
Zones  extend  from  the  isotherms  of  70°  to  those 
of  33".  Tlie  Frigid  Zones  extend  from  these  to 
the  poles. 


TOPICAL  ANALYSIS. 


U.    CLIMATE. 


1,  Main  Elements. 

Causes  which  modify  ciimate. 

2,  Distance  from  the  Equator. 

Results  of  distance  from  the  Equator.  Ellect  on 
annual  temperature-  Climatic  contrasts.  Ex- 
planation. 

3.  Distance  from  the  Sea. 

Insular  and  inland  climates.  Causes  which  moder- 
ate insular  climates.  Rc;isons  for  the  extremes 
of  inland  climates. 

4.  Prevailing  Winds  and  Ocean  Currents. 

Illustrations. 

6.  Height  above  the  Sea  level. 

Effect  of  elevation.  Cause  of  increase  of  cold  with 
elevation.    General  rule. 


6.  Isothermal  lines. 

Represent  what.    Relation  to  parallels.    Zones  of 
temperature. 

Test  Questions.— How  do  the  regions  dejlcient  in  moisture  com- 
pare in  extent  with  those  deficient  in  temperature  ?  IIow  would  in- 
crease of  moisture  affect  the  temperature  of  desert  regions  ?  How  can 
ocean  currents  affect  climates  as  far  inl;ind  as  they  do  J  In  what  cli- 
mates have  nations  been  most  prosperous  ?  If  the  climate  of  England 
should  become  a  very  dry  tme,  how  would  that  affect  the  temperature  ? 


IlL    WINDS  AND  CIRCULATION  OF   THE 
AIK. 

1.  Air  in  Motion. — Tlie  ocean  of  air,  like 
the  ocean  of  water,  is  never  at  rest.  It  has  its 
waves  and  its  currents. 


ANEMOMETER. 


A  body  of  air  in  motion  is  called  wind.*  As  we 
all  know  veiy  well,  the  wind  travels  at  various 
rates  and  in  many  different  directions.  By  means 
of  an  instrument  called  the  anemometer ,  it  has 
been  ascertained  that  the  velocity  of  a  light  wind 
is  five  miles  an  hour;  of  a  "stiff  breeze,"  25 
miles  ;  of  a  storm,  50,  and  of  a  huiTicane  from  80 
to  100,  or  even  150. 

Again  :  the  direction  in  which  a  wind  blows  is 
so  constantly  changing  that  we  often  speak  of  the 
winds  as  fickle,  inconstant  and' uncertain.  There 
is,  however,  order  in  the  movemeiits  of  the  atmos- 
phere.    The  fickle  winds  are  obedient  to  laws. 

There  are  causes  which  make  them  blow  with 
greater  or  less  rapidity.  There  are  reasons  why 
they  blow  now  north,  now  south,  east,  or  west. 

2.  Ca^ises  of  Winds. — The  main  causes  of 
winds  are  two  :    (1)  the  unequal  distribution   of 


*  Winds  are  named  according  to  the  quarter  from  which  they  blow. 
A  tvest  wind  comes  from  the  west,  an  mst  wind  from  the  east. 


76 


WINDS  AND  CIRCULATION  OF  THE  AIR. 


heat  in  the  atmosphere;  and  (2)  the  unequal  dis- 
tribution of  \'apor  in  tiie  atmosphere. 

Effect  of  Heat. — Let  us  consider  the  effect 
of  the  unequal  distribution  of  lieat  in  tlie  atmos- 
phere. If  a  lire  be  lighted  on  the  hearth,  the  air 
in  the  chimney  will  be  heated  and  forced  up  the 
chimney  by  an  indraught  of  cooler  and  heavier  air 
from  all  parts  of  the  I'oom.  Tliis  continues  as 
long  as  the  fire  burns. 

The  same  thing  occurs  when  a  bonfire  is  lit,  or 
a  house  is  on  fire.  Every  child  knows  that  "  the 
sparks  fly  upward  to  the  sky."  They  are  carried 
up  by  the  hot  ascending  current.  The  air  above 
the  fire  is  expanded,  rendered  lighter,  and  driven 
upward  by  currents  of  cool  air  that  come  rushing 
in  from  all  sides.  These,  when  heated,  ascend 
with  such  force  as  to  carry  up  clouds  of  smoke 
and  sjjarks. 

This  unequal  distribution  of  heat,  the  warming 
of  tlie  air  in  the  chimney  or  above  the  burning 
house,  while  tliat  in  the  room  or  in  the  space 
about  tlie  burning  house  is  comparatively  cold, 
establishes  a  system  of  air  currents. 

If  there  are  no  obstacles  in  the  way  of  these  currents, 
and  if  they  are  not  chilled  or  heated  in  their  course,  they 
will  go  straight  toward  the  mouth  of  the  chimney.  Chairs 
and  tables  and  other  objects  in  the  room  will  deHect  them 
and  cause  more  or  less  irregularity  in  their  direction. 

To  prove  that  such  currents  really  do  flow,  place  a  lighted 
candle  in  the  doorway  of  a  room  in  which  a  fire  is  burning. 
You  will  see  the  flame  drawn  inward  by  the  inflowing  cur- 
rent. 

Now  what  occurs  in  the  air  of  a  room  when  a 
fire  is  kindled  on  the  hearth  takes  jjlace  in  tlie  at- 
mosphere. Some  iDortions  of  it  are  always  more 
heated  than  others ;  and  the  unequal  distribution 
of  heat  establishes  a  system  of  currents.  The 
heated  surface  of  the  earth  warms  the  air  above  it. 
This  air,  forced  up  by  tlie  surrounding  cool  air, 
ascends  as  a  current ;  and  streams  of  cooler,  heavier 
air  flow  in.  Just  in  proportion  to  the  size  of  the 
area  heated,  the  volume  of  the  inflowing  currents 
will  be  greater  or  less,  and  in  proportion  to  the 
difference  of  temperature  between  the  heated  air 
and  the  inflowing  currents,  the  rapidity  of  their 
flow  will  be  greater  or  less. 

Effect  of  Moisture.— Tlie  effect  of  unequal 
distribution  of  moisture  is  similar  to  that  of  un- 
eqnal  distribution  of  heat.  Vapor  of  water  is  only 
about  half  as  heavy  as  dry  air  at  the  same  tempera- 
ture. Evidently,  therefore,  if  there  is  much  vapor 
in  any  jiart  of  the  atmospliere,  that  part  will  be- 
come lighter  than  the  neighboring  portions.  Like 
the  air  heated  by  the  fire,  it  will  be  forced  upward 
as  an  ascending  current,  and  there  will  be  an  in- 
rush of  drier,  heavier  air  to  supply  its  place. 


In  general,  the  two  causes  above  mentioned 
operate  together,  for  it  is  natural  that  where  there 
is  most  heat,  there  is  also  most  vapor  present  in 
the  atmosphere.  For  this  reason,  and  because  the 
effect  of  the  two  is  so  similar,  it  will  not  be  neces- 
sary to  consider  in  detail  the  effect  of  vapor  as  a 
cause  of  air-currents. 

3.  General  Circulntion  of  the  Atinos- 
jihere. — Let  us  now  turn  our  attention  from 
these  simple  illustrations  to  what  is  going  on  in 
the  atmosphere  at  large. 

Within  the  tropics  there  is  perpetual  summer. 
The  vertical  rays  of  the  sun  are  incessantly  heat- 
ing the  torrid  zone  and  its  atmosphere,  and  filling 
the  air  with  vapor,  while  the  air  on  either  side  of 
that  zone  is  comparatively  dry  and  cold.  Wliat 
must  be  the  effect  of  this  unequal  distrihition  of 
heat  ami  vapor?  It  creates  a  general  circulation 
of  tite  afmosj^herc. 

In  the  first  jjlace,  as  in  the  case  of  the  fire  upon 
the  hearth,  tlie  heated,  moist  air  of  the  tropics  is 
pressed  upon  by  tlie  heavier  air  on  either  side.  It 
is  forced  upward,  and  there  is  an  indraught  both 
from  the  north  and  the  south  to  supply  its  place. 

Xow,  if  the  earth  were  at  rest,  and  if  its  sur- 
face were  covered  with  water,  the  inflowing  cur- 
rents would  go  straight  from  the  polar  to  the 
equatorial  regions.  There  would  then  be  a  simple 
circulation  of  light  air  from  tlie  equator  to  the 
poles,  and  of  heavy  air  from  the  poles  to  the  equa- 
tor.   The  winds  would  be  steady  and  unvarying. 

Modifying  Causes. — But  the  earth  is  not  at 
rest,  and  its  surface,  instead  of  being  uniformly 
covered  with  water,  is  varied  by  land  masses  of 
greater  or  less  magnitude  and  elevation.  The  ro- 
tation of  the  earth  and  the  influence  of  its  land 
masses  are  two  causes  whicli  largely  affect  the  cir- 
culation of  tlie  air,  and  render  it  exceedingly  com- 
jilicated. 

Winds  are  Classified,  according  to  the  regu- 
larity with  which  they  blow,  as  constant,  variable, 
and  periodical. 

4.  Constant  or  Trade  Winds. — Certain 
of  the  winds  blow  without  interruption  in  the 
same  direction,  and  at  nearly  the  same  rate.  So 
constant  are  they  that  vessels  often  sail  in  them  for 
days  and  days  without,  as  the  sailors  say,  '•  chang- 
ing a  stitch  of  canvas."  It  was  the  steady  blowing 
of  these  wands  which  so  alarmed  the  creAv  of  Co- 
lumbus on  his  first  voyage  to  America,  and  led 
them  to  fear  that  they  should  never  get  back  to 
Europe. 

From  their  importance  to  the  navigator  these 
winds  have  been  called  the  trade  winds  or  trades. 
They  are  currents  of  air  which  are   ceaselessly 


WINDS  AND  CIRCULATION  OF  THE  AIR. 


77 


winging  their  flight  from  the  polar  and  temperate 
regions  toward  the  equator. 

Direction. — If  tlie  earth  had  no  daily  motion, 
these  winds  would  blow  on  one  side  of  the  equator 
from  the  north,  on  the  other  from  the  south,  di- 
rectly into  the  equatorial  regions.  But  in  conse- 
quence of  diurnal  rotation,  the  air,  when  it  arrives 
at  the  equator,  is  in  a  region  which  is  moving 
toward  the  east,  120  miles  an  liour  faster  than  the 
region  in  latitude  30°,  where  it  began  to  blow  as 
a  trade  wind. 

During  its  whole  journey  to  the  equator  the  wind 
lags  a  little  behind,  and  the  eartli,  wliich  is  revolv- 
ing from  west  to  east,  is  slipping  from  under  it  all 
the  time,  so  that 
the  wind  appears 
to  come  from  the 
east.  Thus  an  ad- 
ditional motion  is 
imparted  to  it — 
viz.,  a  motion  to- 
ward the  west ; 
and  so  it  is  made 
to  come  from  the 
northward  and 
eastward  on  the 
north  side,  instead 
of  directly  from 
the  north ;  and 
from  the  south- 
ward and  eastward 
on  the  south  side, 
instead  of  directly 
from  the  south. 

Thus  we  have 
the  tioo  si/ste?ns  of 
trades;  the  north- 
east iini  the  south- 
east. The  north- 
east trades  blow 
from  about  the 
parallel     of     30° 

north,  to  the  equator ;  the  southeast  trades  from 
about  the  parallel  of  30°  south,  to  tlie  equator. 
Both  extend  entirely  round  the  world. 

5.  Variable  Winds.— North  and  south  of 
the  trades  are  the  zones  of  the  variable  winds. 
They  extend  from  the  parallels  of  30°  north  and 
soutli,  to  the  polar  circles.  Within  these  limits 
the  winds  blow  witliout  regularity.  Two  systems 
contend,  and  sometimes  the  one  prevails,  some- 
times the  other.  These  contending  winds  are  the 
counter  trades,  which  blow  from  tlie  equator,  and 
the  polar  winds,  wliich  blow  from  the  poles.  The 
variable  winds  are  designated  on  the  chart,  p.  79, 
as  polar  and  equatorial  winds. 


-~~-:::x: 


CIRCULATION    OF    THE    ATMOSPHERE. 


Diagram   showing  course   of  currents   of   air   from   the   equator   to   the 
poles  and  back.     Let  the  pupils  all  draw  from  niemorj'  similar  diagrams. 


Counter  Trades. — Referring  to  the  chart,  you 
see  that  on  the  jjolar  side  of  the  trade  winds,  the 
arrows  show  that  the  prevailing  direction  of  the 
winds  is  counter  or  opposite  to  tliat  of  the  trades 
— that  i.s,  from  tlie  southward  and  westward  in  the 
northern,  and  from  the  northward  and  westward 
in  the  southern  hemisphere.  For  tliis  reason  these 
westerly  winds  are  called  the  counter  trades. 

Origin. — Tlie  origin  of  these  winds  is  interest- 
ing. It  is  thus  explained.  AVliile  the  trades  blow 
steadily  from  the  poles,  there  must  be  return-cur- 
rents from  the  equator  to  the  poles,  otherwise  the 
polar  regions  in  time  would  be  destitute  of  air. 
When  the  upward  current  at  the  equator  has  risen 

to  a  considerable 
elevation  above 
the  surface  of  the 
earth,  it  divides 
and  flows  toward 
the  poles,  one 
volume  going  to- 
ward the  north, 
the  other  toward 
the  soutli  pole. 

These  two 
streams  of  air  re- 
main tiijper  cur- 
rents as  far  as 
the  northern  and 
southern  limits  of 
the  trade  winds — 
i.  e.,  about  as  far 
as  the  parallels  of 
30°  north  and 
south. 

When, however, 
tliey  have  gone  so 
far  on  their  north- 
ward and  south- 
ward journey,  they 
descend  to  the 
surface  of  the 
earth,  jirobably  for  the  reason  that  their  tempera- 
ture has  fallen  below  that  of  the  air  which  is  flow- 
ing from  the  poles.  They  now  flow  as  surface 
winds  and  constitute  the  counter  trades. 

Proofs. — That  the  upper  currents  above  alluded  to  do  flow 
out  northward  and  southward  from  the  equatorial  regions  is 
abundantly  proved.  Sometimes  volcanoes,  as  we  have  al- 
ready learned,  eject  vast  quantities  of  dust.  Not  unfre- 
quently  this  passes  into  very  elevated  regions  of  the  atmos- 
phere ;  and  instances  are  on  record  of  its  being  carried 
sometimes  for  hundreds  of  miles  in  a  direction  opposite  to 
tliat  of  the  surface  winds. 

Coseguina,  in  Guatemala,  is  in  the  region  of  the  nortli- 
east  trades.  During  tlie  eruption  of  1835,  its  ashes  were 
carried  to  the  island  of  Jamaica.  Jamaica  is  800  miles 
northeastward  of  Coseguina.     No  other  explanation  of  this 


78 


WINDS    AND   CIRCULATION    OF    THE    AIR. 


is  possible,  except  that  an  upper  current  was  blowing  above 
the  surface  winds,  in  a  direction  opposite  to  theirs. 

Again,  in  1815,  aslies  from  a  volcano  in  the  island  of  Sum- 
bawa,  near  Java,  were  borne  to  the  island  of  Amboyna,  800 
miles  to  the  eastward,  although  the  southeast  wind  was  then 
at  its  height.  This  again  proves  that  there  must  have  been 
a  powerful  current  toward  the  northeast,  above  the  southeast 
surface-wind.  It  is  clear,  therefore,  that  return  currents 
flow  from  the  equator  to  the  poles,  as  indicated  on  the  chart. 
We  shall  see  in  the  following  paragraphs  what  becomes  of 
these  return  currents. 

Direction. — Were  it  not  for  the  earth's  rota- 
tion, the  counter  trades  would  move  straiglit  to  the 
poles.  But  rotation  lias  upon  them  a  similar  ef- 
fect to  tliat  which  it  has  upon  the  trades.  It 
changes  their  direction,  and  it  gives  them  motion 
from  the  westward.  This  is  ex])lained  as  follows  : 
while  in  the  equatorial  regions,  these  winds  have 
acquired  the  rapid  rotary  motion  toward  the  east 
which  belongs  to  those  regions.  Hence,  when  they 
reach  latitudes  nearer  the  poles,  they  are  blowing 
to  the  eastward  witli  a  velocity  far  more  rapid  than 
that  which  belongs  to  the  latitudes  which  they  have 
reached,  and  thus  they  become  westerly  winds. 

The  Polar  Winds  are  currents  of  cold  air 
making  their  way  from  the  poles  toward  the  equa- 
tor. Their  direction  is  similar  to  that  of  the  trade 
winds,  northeast  in  the  northern  hemis^jhere,  and 
southeast  in  the  southern  hemisj)here.  Coming 
from  the  equator,  the  counter  trades  bring  moist- 
ure and  warmth  ;  the  polar  winds  are  dry  and  cold. 

The  trades,  counter  trades  and  polar  winds, 
though  treated  separately,  are  really  only  parts  of 
the  same  great  atmospheric  current  which  is  cease- 
lessly accomplishing  its  unending  circuit  from  the 
equator  to  the  poles,  and  from  the  poles  back  to 
the  equator,  as  shown  in  diagram  on  p.  77. 

6".  Hie  Calm,  Belts. — "When  two  equal  cur- 
rents of  air  meet,  a  calm  is  produced.  Over  the 
equator,  where  the  northeast  and  southeast  trade 
winds  meet,  there  is  a  belt  of  calms  encircling  the 
earth.  It  is  called  the  Equatorial  Calm  Belt. 
This  name  is  not  altogether  a  good  one,  because 
throughout  the  belt  a  vast  current  of  air  is  inces- 
santly ascending.  The  belt  is  calm  in  the  sense  of 
being  comparatively  free  from  horizontal  move- 
ments of  the  atmosphere. 

The  most  difficult  part  of  the  ocean  for  sailing- 
vessels  to  cross  is  this  calm  belt.  Ships  are  some- 
times detained  here  for  many  days. 

As  where  the  northeast  and  southeast  trade 
winds  meet,  so  where  the  trades  and  counter  trades 
meet  and  cross,  there  is,  in  each  hemisphere,  a  belt 
of  atmosphere  marked  by  the  prevalence  of  calms. 
In  the  northern  hemisphere  we  have  the  Calms  of 
Cancer ;  and  in  the  southern  the  Calms  of  Capri- 
corn. 


The  position  of  all  the  calm  and  wind  belts 
above  described  is  not  invariably  fixed.  Tliey  all 
move  northivard  and  southward,  folio ivinri  the  ap- 
parent  march  of  thesvn.  They  reach  their  farthest 
northward  limit  in  autumn,  their  farthest  south- 
ern limit  in  spring. 

7.  The  Periodical  TFtMrfs  are  those  which 
blow  for  a  certain  time  in  one  direction,  and  then 
for  an  equal,  or  nearly  equal  time,  in  the  opposite 
direction.  They  are  the  land  and  sea  breezes,  and 
the  monsoons. 

Land  and  Sea  Beeezes. — All  along  the  sea- 
shore of  warm  countries,  there  is  a  hreeze  from 
the  sea  by  day,  and  one  from  the  land  by  night. 
The  rays  of  the  sun  heat  the  land  more  readily 
than  they  do  the  water.  This  makes  the  land 
warm  in  the  day,  leaving  the  sea  cool ;  the  warm 
rocks,  sand,  and  soil,  heat  and  expand  the  air  in 
contact  with  them  and  render  it  light.  Pressed 
upward  by  the  cooler  air  of  the  sea,  it  rises.  Cur- 
rents then  come  rushing  in  from  the  sea  to  supply 
the  place  of  the  ascending  columns,  precisely  as 
the  indraught  to  a  furnace  supplies  the  rush  up 
the  chimney  :  thus  we  have  the  sect-breeze. 

By  night  the  opposite  effect  occurs.  The  land 
has  the  property  of  radiating — that  is,  of  throwing 
off — its  heat  more  rajiidly  than  the  water  can. 
Hence  the  land  by  night  grows  cooler  than  the 
sea.  It  then  cools  and  makes  heavier  the  air 
above  it.  The  air  above  the  sea  remains  compara- 
tively warm  and  light.  Hence  it  is  jiressed  up- 
ward by  the  cooler  air  of  the  land,  and  currents 
rush  from  the  land  to  the  sea.  This  is  the  land- 
breeze. 


Questions  on  Chart  of  Winds. — (The  red  color  on  the 
chart  indicates  the  constant  or  trade  winds  ;  green,  the 
variable  winds,  or  those  which  blow  alternately  from  the 
equator  and  the  pole  ;  blue,  the  northeasterly  winds  blow- 
ing from  the  pole  ;  yellow,  the  monsoons.) 

Define  the  region  of  the  trades.  What  do  we  find  along 
their  line  of  meeting  ?  Where  else  do  calms  prevail  ?  What 
special  names  are  applied  to  the  calms  ?  Are  the  calms  at 
all  seasons  exactly  where  shown  on  the  chart  ?    WTiy  not  ? 

Where  do  the  great  monsoons  blow  ?  Within  the  region 
of  what  winds  ?    Point  out  other  monsoon  regions. 

How  many  regions  of  typhoons  and  hurricanes  do  you 
find  on  the  chart  ?  Where  are  they  ?  Describe  the  course 
of  the  West  India  hurricanes.     Of  the  Australian. 

What  is  the  direction  of  storms  in  the  regions  north  of 
the  equator  ?    In  those  south  of  the  equator  ? 

What  winds  occasionally  prevail  in  Northern  Africa  ?  In 
the  countries  of  Southern  Europe  ?  Where  do  these  latter 
come  from  ?  Where  does  the  Harmattan  of  Guinea  come 
from  ? 

Trace  the  circulation  of  a  volume  of  air,  supposing  it  to 
start  northward  from  the  equator.  Supposing  it  to  start 
southward.     (See  diagram,  p.  77.) 


8o 


WINDS  AND  CIRCULATION  OF  THE  AIR. 


Were  it  not  for  these  refreshing  breezes,  many 
countries  along  the  sea-shore,  that  are  now  the 
abodes  of  healtli,  prosperity  and  liajopiness,  would 
be  uninhabitable. 

Monsoons. — Monsoons  arc  winds  that  blow 
from  a  certain  direction  for  part  of  tlie  year,  and 
for  the  rest  of  the  year  from,  quite  another  quarter. 
They  are  land  and  sea  breezes  on  a  grand  scale.  In- 
stead of  alternating  with  day  and  night,  and  blow- 
ing a  few  hours  at  a  time,  they  alternate  with 
summer  and  winter. 

The  most  famous  monsoons  are  those  of  South- 
ern Asia.  In  India  they  blow  from  the  northeast 
for  six  months  of  the  year,  and  from  the  south- 
west for  six  months. 

Cause. — During  the  summer  the  sun  plays  upon 
the  great  deserts  and  inland  basins  of  Central 
Asia.  Those  dry  and  barren  wastes  glow  like 
furnaces,  and  the  heated  air  ascends  from  them 
in  immense  columns.  A  disturbance  is  created 
which  is  felt  to  the  distance  of  2,000  or  3,000 
miles  from  its  centre.  Cooler  air  rushes  in  from 
the  sea  on  three  sides  of  the  continent.  Along 
the  coasts  of  Siberia  it  comes  from  the  north. 
From  China  round  the  south  of  the  continent  to 
the  Red  Sea,  it  comes  from  the  Pacific  and  Indian 
Oceans — that  is,  from  the  southeast,  south,  or 
southwest. 

In  this  region,  which  is  largely  in  the  zone  of 
"trades,"'  the  effect  is  so  great  as  actually  to  re- 
verse the  trade  wind  and  cause  it  to  blow  in  the 
contrary  direction. 

In  the  winter  the  centre  of  Asia  is  a  region  of 
low  temperature.  Its  atmosphere  is  dry,  cold, 
and  heavy.  That  of  the  seas  surrounding  the 
continent  is  moist,  warm,  and  light.  The  liglit  air 
is  pressed  ujiward  by  the  heavy,  and  ascends  into 
the  upper  regions  of  the  atmosphere.  Currents  then 
blow  from  the  land  toward  the  sea.  In  conse- 
quence of  this  we  have,  during  the  winter  in 
India,  the  noi'theast  monsoons,  which  are  really 
the  northeast  trades,  blowing  with  augmented 
force  and  velocity  ;  on  the  Chinese  coast  we  hav% 
the  northwest  monsoons. 

Effects The  summer   or    the    southeast  and 

southwest  monsoons  having  passed  over  the  sea, 
are  laden  with  moisture,  and  are  the  wet  monsoons. 
They  give  its  ivet  season  to  Southern  Asia.  The 
northeast  and  northwest  monsoons  are  for  the 
most  part  dry,  because  they  come  from  the  land. 
During  their  prevalence  it  is  the  dry  season.  The 
changing  from  the  dry  winds  to  the  wet  is  com- 
monly called  in  India  the  "  bursting "  of  the 
monsoon. 

Burstinf/  of  the  Monsoon. — The  southwest  monsoon  sets 
in  generally  toward  the  end  of  April,  a.  steady  wind  sweep- 


ing up  I'lom  the  Indian  Ocean  and  carrying  with  it  dense 
volumes  of  va])oi'.  The  atriiDsjihcre  becomes  clo^-e  ami  op- 
pressive. Flashes  of  lightning  jilay  from  cloud  to  cloud. 
The  wind  suddenly  springs  up  into  a  tempest.  Then  a  few 
great  heavy  drops  of  rain  fall  ;  the  forked  lightning  is 
changed  to  sheets  of  light,  and  suddenly  the  floodgates  of 
heaven  arc  opened,  and  not  rain,  but  sheets  of  water  are 
poured  forth,  refreshing  the  parched  earth,  carrying  fer- 
tility over  the  surface  of  the  country,  filling  the  wells  and 
reservoirs,  and  replenishing  the  dwindling  rivers  and  streams. 
The  whole  land  from  Cape  Comorin  to  Bombay  seems  sud- 
denly recalled  to  life.  Vegetation  may  almost  be  stjn  to 
grow,  and  from  the  baked  mud  of  the  river-banks  emerge 
countless  fishes,  which  for  weeks  or  months  have  lain  in 
torpor. 

Minor  Monsoons. — Certain  other  winds  that 
resemble  the  monsoons  are  those  of  Australia,  the 
Gulf  of  Guinea,  and  the  Mediterranean. 

The  winds  of  Australia  blow  landward  in  the  hot  months; 
seaward  in  the  cold  season. 

Over  the  Gulf  of  Guinea  and  the  Mediterranean  periodi- 
cal winds  blow  in  summer  in  opposite  directions;  the  winds 
of  the  Gulf  of  Guinea  come  from  the  southwest,  those  of  the 
Mediterranean — knomi  as  the  Etesian  winds — are  from 
the  northeast.  Both  are  due  to  one  cause,  viz.,  the  intense 
heating  of  the  Sahara.  This  produces  an  upward  current  of 
heated  air  and  an  inrush  of  cooler  air  from  the  Gulf  of 
Guinea  on  the  one  side  and  from  the  Mediterranean  on  the 
other. 

The  periodical  winds  of  Mexico,  Central  America,  and 
the  Brazilian  waters,  and  those  known  in  Texas  as  "Xorth- 
ers,"  are  due  to  causes  similar  to  those  of  the  monsoons. 

Other  Periodtc  Winds  of  less  importance  are 
what  we  may  call  the  return  currents  from  the 
deserts.  These  are  laden  with  heat  and  sand  and 
dust. 

From  the  Sahara  currents  flow  northward  and  southward. 
Those  from  the  south  enter  Egypt,  and  blow  for  a  few  days 
at  a  time  during  a  period  of  fifty  days.  Hence  they  are 
called  khamsin,  an  Arabic  word  meaning  fifty.  During 
their  prevalence  the  air  is  filled  with  blinding  dust  and  the 
midday  sun  is  darkened.  By  such  a  wind  of  unusual  vio- 
lence, the  army  of  Cambyses,  50,000  In  number,  is  said  to 
have  been  destroyed,  when  on  its  way  to  attack  the  oasis  and 
temple  of  Jupiter  Ammon. 

Crossing  the  Mediterranean,  the  desert  wind  scorches  the 
vegetation  of  Southern  Europe.     It  is  known  as  the  sirocco. 

From  the  deserts  of  Syria  and  Arabia  comes  the  dreaded 
simoom,  a  suffocating  wind  which  often  heaps  up  vast 
mounds  of  sand,  and  completely  buries  whole  caravans  of 
travellers. 

Mountain  Winds. — The  tops  of  mountains  chill 
the  surrounding  air.  Tliis  sometimes  descends  as 
a  cold  wind  into  the  warmer  regions  below.  Thus 
from  the  snowy  heights  of  the  Andes  the  cold 
jjamjjeros  sweeji  over  the  Pampas  of  the  Eio 
Plata,  and  the  icy  2}una  descends  upon  the  table- 
land of  Peru. 

S.  Offices  of  Winds. — Three  offices  of  winds 
may  be  mentioned  :  (1)  they  keep  the  elements 
of  the  atmosphere  uniformly  mixed  by  maintain- 


STORMS. 


81 


ing  a  constant  circulation  ;  (2)  they  bear  yapor 
from  the  sea  to  the  land,  and  thus  water  the  earth  ; 
(3)  they  carry  heat  imprisoned  in  the  jmrtielos  of 
vapor,  from  the  overlieated  regions  of  the  earth  to 
the  colder  ones,  and  in  this  way  make  the  torrid 
regions  cooler,  and  the  temperate  and  polar 
warmer  than  they  would  otherwise  be.  Discharg- 
ing these  various  offices,  they  verify  the  Psalmist's 
words,  '^  God  maketh  the  winds  his  messengers." 

TOPICAL  ANALYSIS. 
III.    WINDS   AND   CIRCULATION   OF   THE   AIR. 

1.  Air  in  Motion. 

Wind.  Velocity  of  differeut  winds.  Order  in  the 
winds. 

2.  Causes  of  Winds. 

Effect  of  heat.    Of  moisture. 

3.  General  Circulation  of  the  Atmosphere. 

Location  of  constant  ascending  currents.  Causes 
which  complicate  the  circulation.  Classification 
of  winds. 

4.  Constant  or  Trade  Winds. 

General  character.  Direction.  Cause  of  their  west- 
ward trend. 

5.  Variable  Winds. 

Locality.  Counter  trades.  Origin.  Proofs.  Direc- 
tion.   Polar  winds. 

6.  The  Calm  Belts. 

Equatorial.  Calms  of  Cancer.  Of  Ciipricorn.  An- 
nual movement  of  calms  and  winds. 

7.  Periodical  Winds. 

Land  and  sea  breezes.  Benefits  of.  Monsoons. 
Cause.  Effect.  Bursting  of  monsoon.  Minor  mon- 
soons.   Other  periodic  winds.     Mountain  winds. 

8.  Offices  of  Winds. 

Test  Questions.— What  is  in  general  the  "circuit"  of  the  winds  ? 
Their  general  effect  upon  climate  ?  What  force  is  the  primary  cause  of 
wlnd.s  ?  Wliat  other  force  acts  as  auxiliary  ?  Can  you  give  any  reason 
why  the  ocean  of  air  is  so  much  disturbed  at  the  bottom,  while  thL' 
ocean  of  water  is  disturbed  chiefly  nt  or  near  the  surface  ?  Should  the 
solar  heat  diminish,  what  would  be  the  effect  on  the  winds  ? 


IV.    STOEMS. 

1.  General  Description. — Storms  or  tem- 
pests are  sudden  and  violent  commotions  of  the 
atmosphere.  Especially  at  sea  they  are  among  the 
most  grand  and  terribly  sublime  spectacles  in  nat- 
ure. A  wind  becomes  a  storm  when  it  attains  the 
velocity  of  fifty  miles  or  more  an  hour. 

Tlie  great  storms  of  the  "West  Indies  and  of  the 
Indian  Ocean  are  called  hurricanes  and  tornadoes; 
those  of  the  Chiiia  Sea,  typlioons.  [See  Chart  of 
the  Winds.]  Tliese  are  alike  in  cause  and  charac- 
ter, and  may  best  be  considered  under  the  general 
name  of  cyclone.     This  name,  derived  from  the 


Greek  huMos,  circle,  refers  to  the  fact  that  they 
consist  of  columns  of  air  revolving  round  a  perjjcn- 
dicular  axis.  At  the  same  time  they  have  a  pro- 
gressive motion  of  greater  or  less  rapidity  over  a 
certain  portion  of  the  surface  of  the  earth. 

Tllusiraiion. — You  have  noticed,  especially  in  autumn,  lit- 
tle whirlwinds  travelling  along  the  roads  or  through  the 
fields,  and  raising  eddying  or  wliirling  columns  of  leaves 
and  dust  to  a  great  height.  These  an;  miniature  cyclones. 
They  have  both  a  revolving  motion  and  a  progressive  one. 

2.  Cause  of  Htonns. — The  general  cause  of 
all  such  atmospheric  disturbances  is  the  same  in 
principle  as  that  of  ordinary  winds.  It  is  a  differ- 
ence or  inequality  of  jiressure  or  weight,  in  difEerent 
regions  of  the  atmosphere.  Tlie  principle  may  be 
thus  stated  :  into  an  area  of  low  harometer  a  wind 
must  always  How  from  an  area  of  high  barometer. 

When  from  any  cause  the  weight  of  the  atmos- 
phere in  a  locality  is  diminished,  an  ascending 
curi'ent  results.  Currents  of  colder  iind  heavier 
air  rush  in  to  supply  the  deficiency.  The  force 
and  velocity  of  the  currents  thus  created  will  be 
greater  or  less  according  to  the  difference  of  atmos- 
pheric pressure,  or  the  "  gradient,"  as  meteorolo- 
gists call  this  difference.  The  larger  the  gradient, 
the  more  violent  will  be  the  rosultina:  wind. 


COUHSES    OF    CYCLONES. 


Now  suppose  there  is  one  area  of  low  barometer 
and  one  of  high  ;  the  result  will  be  a  simple  wind 


82 


STORMS.    ' 


having  one  direction.  But  if  the  one  area  of  low 
barometer  have  areas  of  high  barometer  on  all 
sides  of  it,  it  is  clear  that  fz-om  every  one  of  these 
a  current  will  flow  in  upon  the  area  of  low  barom- 
eter. Such  in-coming  currents  of  air  do  not  pass 
in  straight  lines  to  the  centre  of  the  area  of  low 
barometer,  but  circle  round  it  in  an  ever-narrow- 
ing spiral,  gradually  ascending  as  they  approach 
the  centre.  They  constitute 
the  cyclone. 


Jlhtsiraiion. — The  curves  de- 
scribed by  the  air-currents  ol  a  cy- 
clone may  be  readily  illustrated. 
Pill  a  basin  having  a  stopper  in 
the  bottom  with  water.  Remove 
the  stopper  and  observe  how  the 
water-currents  take  descending 
spiral  courses.  They  move  round 
the  centre,  but  they  also  move  to- 
ward the  centre.  They  are  Hke 
the  air-currents  of  a  cyclone  turned 
upside  down. 

The  belief  is  gaining  ground 
that  cyclones  are  largely  due  to 
electrical  disturbances.  Some 
very  interesting  experiments  seem 
to  corroborate  this  view. 


NORTHERN  HEMISPHERE 

WindEasf 


(2)  The  storm,  while  revolving,  (ravels  forward. 
The  direction  of  this  progressive  motion  is  in  gen- 
eral northwest  and  southwest  within  the  zones  of 
the  trades,  and  northeast  and  southeast  in  those 
of  the  counter-trades. 

The  course  of  land  cyclones  is  not  necessarily  horizontal 
or  paraUel   to   the   surface  of  the   earth.     The   revolving 
column  appears  frequently  to  dip  down  at  certain  jwints  in 
the  line  of  its  progress,  and,  again 
rising,  leaves  long  distances  un- 
touched. 


Ni 


3.  Laws  of  Storms. — 

Cyclones  obey  the  following 
well  ascertained  laws : 

(1)  The  tvind  revolves  in 
ojyposite  directions  according 
as  the  cyclone  is  in  the  nor- 
thern or  southern  hemisphere. 
In  the  northern  the  direction 
of  revolution  is  from  right  to 
left,  or  against  the  hands  of 
a  watch.  In  the  southern  it 
is  from  left  to  right,  or  with 
the  hands  of  a  watch.  This 
is  shown  in  the  diagram,  page 
81. 

The  direction  of  the  whirl 
seems  to  be  due  to  the  influ- 
ence of  the  rotation  of  the 
earth  upon  the  air-currents, 
which  press  from  all  adjacent 
quarters  into  the  areas  of  low 
barometer,  and  to  the  action  of  these  currents  one 
upon  another. 

As  the  wind  revolves  in  a  spiral,  it  constantly  changes  its 
direction  at  any  given  place  in  the  storm -track,  in  the  same 
way  as  the  various  parts  of  a  moving  carriage-wheel  do.  On 
opposite  sides  of  the  centre  it  has  opposite  directions.  Hence 
we  see  why  the  wind  changes  as  soon  as  the  storm-centre 
passes.     This  is  shown  liy  the  "storm  cards  "  on  this  page. 

The.  rate  of  revolution,  or  "  velocity  of  the  wind,"  is  from 
50  to  150  miles  an  liour. 


SOUTHERN  HEMISPHERE 

VJind  West 


The  starting  point  of  cy- 
clones is  in  the  tropics. 
North  of  the  equator  they 
move  northwestwardly  up  to 
about  latitude  30°  N.  Here 
they  turn  to  the  northeast. 
South  of  the  equator  they 
pursue  the  reverse  course  ; 
starting  near  the  tropics  they 
advance  toward  the  south- 
west, and  near  the  parallel 
of  27"  they  turn  to  the  south- 
east. From  this  it  will  be 
seen  that  the  pathway  of  cy- 
clones somewhat  resembles 
the  curve  called  a  parabola. 
[See  diagram,  p.  81.] 

The  rate  of  travel  is  from  one  to 
forty-five  miles  an  hour,  though 
storms  are  sometimes  stationary 
for  a  considerable  time. 


Wind  East 


STORM   CARDS. 

(Showing  direction  of  whirl  in  both  hemispheres.) 


(3)  The  storm-centre  is 
an  area  of  calm,  and  also  of 
low  barometer.  The  arrival 
of  the  storm-centre  at  any 
point  is  indicated  by  the 
barometer.  The  descent  of 
the  mercury  in  tropical 
storms  often  amounts  to  two 
inches.  It  is  sometimes  so 
rapid  that  it  can  be  detected 
by  the  eye. 

Let  us  see  why  this  fall  of 
the  barometer  should  occur 
at  the  storm-centre.  For 
reasons  not  well  understood 
the  atmosphere  at  this  point  of  the  storm  area 
is  most  largely  charged  with  vapor,  and  here  the 
rainfall  is  usually  heaviest.  Now  moist  air  is  light, 
because  vapor  of  water  is  only  about  half  as  heavy 
as  dry  air.  Therefore  the  greater  the  proportion 
of  vapor  which  the  air  contains,  the  lower  will  be 
the  barometer. 

Furthermore,  the  rainfall  itself  contributes  to 
depress  the   barometer    by    the   condensation    of 


STORMS. 


83 


STORM    AT    ST.    THOMAS,  OCTOBEB,    1867. 


aqueous  vapor  into  rain-drops,  and  by  the  conse- 
quent liberation  of  latent  heat. 

Such  appear  to  be  some  of  the  reasons  why  the 
storm-centre  is  an  area  of  loio  barometer. 

If  from  a  series  of  observations  we  know  wliat  has  been 
the  position  of  the  stonn-centve  for  every  day  during  the 
continuance  of  the  storm,  we  may  readily  map  down  the 
track  of  the  cyclone. 

Irregularity  of  Land  Storms. — Tlie  above  laws 
apply  with  more  exactness  to  storms  at  sea  than 
to  those  on  land.  The  comjjarative  irregularity  of 
land  storms  is  mainly  due  to  two  causes  :  (1)  on 
land,  such  obstacles  as  mountains  and  hills  change 
the  direction  of  storms  and  the  wind  currents  of 
which  they  consist ;  (3)  the  air  on  the  land  is 
more  irregularly  heated  than  over  the  sea,  and 
areas  of  heated  air  and  low  barometer  must  attract 
storms  out  of  their  normal  course. 

Storm  at  St.  Thomas.— On  the  29th  of  October,  1867, 
tlie  isUmd  of  St.  Thomas  was  visited  by  a  cyclone  of  marked 
violence.     [See  diagram  above.] 

In  the  morning  thei'e  was  nothing  unusual  in  the  apjicar- 
ance  of  the  weather.  The  barometer  stood  at  30.  At  11 
o'clock,  and  without  any  warning  from  the  barometer,  a 
gale  sprang  up  from  the  northwest.  It  blew  for  an  hour. 
Then  there  was  a  great  calm,  which  lasted  13  minutes. 
The  barometer  now  fell  more  than  two  inches. 

This  showed  that  the  centre  of  the  storm,  the  area  of 
quick  and  copious  condensation  and  rainfall,  had  reached 
the  island.  So  dense  was  the  body  of  rain  and  spray  which 
now  filled  the  streets  that  objects  20  yards  away  were 
rendered  invisible,  and  persons  seeking  their  homes  held  on 
to  lamp-posts,  door-handles,  or  whatever  promised  tempo- 
rary security,  uncertain  which  way  to  turn  in  the  darkness 
and  the  flood. 

The  13  minutes  of  calm  were  the  time  during  which  the 
storm-centre  was  travelling  over  the  island.     When  it  had 


passed,  there  was  a  change  in  the  wind.  It  had  blown  from 
the  northwest ;  it  now  came  from  the  southeast.  The  storm 
at  this  time  reached  its  height. 

The  bark  was  blown  from  the  trees,  and  the  masts  of 
ships  were  literally  whipped  out  of  them.  Every  vessel  in 
the  harbor  was  wrecked,  stranded,  or  dismasted.  Large 
blocks  of  stone  were  lifted  from  the  earth  and  blown  about 
the  sti'eets.  Houses  were  unroofed  or  carried  along  by  the 
wind ;  and  in  the  short  space  of  four  hours  thousands  of 
persons  had  been  rendered  houseless,  75  vessels  had  been 
wrecked  or  crippled,  and  114  lost. 

The  little  island  of  Tortola  happened  to  lie  in  the  track  of 
this  storm.  Entire  villages  were  blown  away;  scarcely  a 
hut  was  left  standing. 

This  storm  continued  its  course  to  the  westward,  passing 
over  Porto  Rico,  and  reaching  the  Island  of  Hayti  the  next 
day,  where  again  it  was  very  destructive. 

4.  Value  of  Sforui  Laws. — A  knowledge 
of  the  laws  of  storms  is  of  the  utmost  value  to  the 
navigator.  By  observing  the  direction  of  the  wind 
he  may  learn  in  what  direction  the  storm-centre  is 
from  him.  The  rule  for  this  is  :  turn  your  back  to 
the  wind,  and  the  low  barometer  is  always  to  your 
left  in  the  northern  hemisphere,  and  in  the  south- 
ern hemisphere  to  your  right.  This  will  readily  ap- 
pear by  examining  the  diagram  on  Jjage  81,  and 
imagining  yourself  with  your  back  to  the  arrow 
heads.  If  the  sailor  knows  whereabouts  the 
storm-centre  is,  he  knows  how  to  steer  away 
from  it. 

Again  :  suppose  he  finds  his  barometer  sinking 
rapidly,  an  inch  or  even  two  inches  below  its 
usual  height.  He  now  knows  that  he  is  in  the 
storm-centre.  Obviously  it  will  be  well  to  trim 
the  sails  and  prepare  for  a  gale.  The  centre  of 
calm  will  soon  pass  beyond  liim  and  a  tempest  will 
strike  him. 


84 


STORMS. 


3.  TJie  Areas  of  Storms  difEer  in  size  and 
shape.  Though  iu  general  circular,  tliey  are  fre- 
quently elliptical  ;  as,  for  example,  in  tlie  United 
States,  where  their  shape  is  a  very  elongated  oval. 
As  to  size,  they  are  seldom  less  than  six  hundred 
miles  in  diameter,  and  usually  average  twice  that 
amount. 

6'.  Wliirlwinds  and  Tornadoes  difEer 
from  hurricanes  and  typhoons,   (1)  in  duration; 

(2)  extent  of  area ;  and  (3),  sometimes  at  least, 
in  direction  of  the  wliirl.  They  seldom  last  long  ; 
often  not  more  tlian  a  minute.  Tlieir  breadth 
varies  from  a  few  Iiundred  yards  to  a  mile  or  two, 
and  their  course  is  ordinarily  not  more  than 
twenty-five  miles  in  length.  The  direction  of 
their  whirl  depends  on  the  direction  of  the 
stronger  of  the  two  currents  wliich  produce  them. 
Whirlwinds  and  tornadoes  not  unf  requently  visit 


WATEIl-SPOUT   AT   SEA. 


large  areas  of  the  Mississippi  Valley.  Tliey  sweep 
everything  before  them.  Houses  are  lifted  np 
bodily,  and  lanes,  called  "wind-roads,"  are  made 
through  the  forests.  Large  trees  are  uprooted  ; 
they  are  whirled  about  in  the  air  like  stubble,  and 
often  left  with  their  tops  pointing  toward  the  place 
from  wliich  their  roots  have  been  torn. 

Dust  Whirhvinds. — Passing  over  desert  regions 
they  give  rise  to  the  phenomena  known  as  dust 
whirlwinds.  Those  of  India  are  tlic  most  singular. 
They  consist  of  a  single  column  of  sand,  or  of  a 


multitude  of  such  columns,  each  revolving  upon 
its  axis.  These  sometimes  range  themselves  to- 
getlier  side  by  side  and  rapidly  advance,  envelop- 
ing everything  in  midnight  darkness,  and  covering 
the  unwary  spectator  with  a  deluge  of  sand. 

Waterspouts. — At  sea  whirlwinds  sometimes 
2)roduce  waterspouts.  They  correspond  to  the 
dust  whirlwinds  of  the  desert.  The  air-current, 
revolving  like  that  of  a  cyclone,  in  an  upward 
sjjiral,  takes  iij)  llie  spray  of  the  waves,  and  a  tall 
column  may  be  seen  revolving  on  its  axis  and 
moving  over  the  waters  with  extraordinary  speed. 

7.  Uistribution  of  Storms.— [See  Chart 
of  the  Winds.]  The  most  violent  storms  occur  in 
the  vicinity  of  mountainous  islands. 

The  Pacific  is  the  most  tranquil  of  the  oceans. 
In  those  portions  of  its  trade-wind  regions  where 
there  are  no  islands,  and  where  monsoons  do  not 
prevail,  storms  are  unknown.  The  typhoons  are 
confined  to  the  southeast  coasts  of  Asia  and  the 
East  India  Archipelago. 

The  South  Atlantic,  along  the  coast  of  inter- 
tropical Bi-azil,  is  almost  stormless,  whereas,  in 
nearly  corresponding  latitudes  in  the  North  At- 
lantic, as  on  the  coast  of  Florida,  Central  America, 
Mexico,  and  the  West  Indies,  terrific  hurricanes 
occur. 

The  portions  of  the  Indian  Ocean  specially  sub- 
ject to  hurricanes  are  the  Bay  of  Bengal  and  the 
neighborhood  of  Mauritius. 

S.  Weather  Foreeasts.* — During  the  last 
thirty  years  growing  attention  has  been  paid  by 
scientific  men  to  the  subject  of  the  weather.  Ob- 
servations, more  or  less  systematic,  have  been  made 
uj5on  the  force  and  direction  of  the  wind,  the  course 
and  character  of  storms,  the  pressure  of  the  at- 
mosjihere,  the  amount  of  rainfall,  the  temperature 
and  moisture  of  the  air,  and  meteorological  phe- 
nomena in  general.  The  multitudinous  observa- 
tions made  have  disclosed  to  meteorologists  cer- 
tain general  jjrinciples  which  may  perhaps  be 
called  laws  of  the  weather. 

Knowing  these  laws,  and  knowing  by  tele- 
graphic reports  the  weather-conditions  prevailing 


*  Thirty  years  ago  the  author  of  this  work  urged  upon  the  attention 
of  the  government  of  the  United  States,  and  tliose  of  European  nations, 
the  desirability  of  having  systematic  meteorological  observations  car- 
ried on  by  all  nations  at  sea.  As  the  result  of  his  efforts  the  United 
States  government  invited  all  the  maritime  States  of  Christendom  to  a 
conference,  which  looli  place  in  Brussels,  1853,  and  which  adopted  the 
suggestions  made.  But  the  ideas  of  Lt.  Maury  were  not  limited  to  the 
ocean. 

In  ihe  preface  to  the  second  edition  of  his  "Physical  Geogiaphy  of 
the  Sea,"  published  in  1855,  he  says  "  it  is  a  pity  that  the  system  of 
observations  recommended  l)y  the  conference  should  relate  only  to  the 
sea.  The  plnn  should  include  tlic  land  also,  and  be  universal."  Only 
a  short  time  before  liis  death  he  delivered  a  lecture  on  this  topic  is 
Boston,  and  jmotltor  in  St.  Louie. 


STORMS. 


85 


throughout  the  country,  we  are  enabled  to  predict 
from  day  to  day,  with  considerable  accuracy,  the 
approach  of  storms,  or  of  cold  or  hot  weather. 
We  shall  now  briefly  consider  the  way  in  which  this 
is  done  by  the  Signal  Service  of  the  United  States. 

Great  Storms  of  the  United  States. — Most 
of  our  great  storms  consist  of  northeasterly  winds, 
and  travel  in  a  northeasterly  direction.  They 
may  be  conveniently  classed  as  those  which  come 
to  us  from  the  Pacific  Ocean,  and  those  which 
come  from  the  Atlantic. 

The  storms  of  the  Pacific  penetrate  to  a  greater 
or  less  distance  into  the  country,  and  often  cross 
it  entirely.  Their  general  direction  is  from  west 
to  east. 

J'he  storms  of  the  Atlantic  are  first  felt  either 
at  some  southerly  point  on  the  Atlantic  seaboard, 
or  on  the  shores  of  the  Gulf.  Generally  they 
come  in  from  sea  by  the  way  of  the  Gulf,  pass 
northward  on  the  west  side  of  the  i\Iississippi  Val- 
ley, or  the  western  slope  of  the  Appalachians,  and 
then  turn  to  the  northeast. 

Those  which  make  their  appearance  first  on  the  Atlantic 
seaboard  are  the  western  halves  of  cyclones,  which,  pursuing 
their  parabolic  course,  first  northwestwardly  and  then  north- 
eastwardly, happen  partially  to  embrace  our  shores  within 
thoir  area.  These  western  half-cyclones  consist  of  northeast 
and  northwest  gales.  The  eastern  halves  of  (he  same  storms, 
consisting  of  gales  from  the  southwest  and  southeast,  are  at 
sea.  The  storm-centre  pursues  a  course  nearly  coinciding 
with  our  shore  line. 

Prediction  of  Storms. — The  transient  and 
altogether  uncertain  character  of  the  tornadoes 
which  occur  in  many  parts  of  our  country  renders 
it  impossible  to  make  any  predictions  regarding 
them.  Lasting  often  for  only  a  few  minutes,  they 
come  and  go  almost  before  we  are  aware  of  their 
existence.  Of  their  cause  and  their  course  it  may 
not  unfairly  be  said  that  nothing  is  known. 

The  behavior  of  ordinary  storms,  however,  is  so 
far  regular,  that,  in  a  large  proportion  of  cases, 
their  course,  after  they  have  once  manifested 
themselves,  may  be  foretold  with  some  degree  of 
accuracy. 

Simultaneous  observations  are  made  at  100  Sig- 
nal Service  stations  scattered  over  the  country, 
at  7  A.M.,  3  P.M.,  and  11  p.m.  every  day.  These 
observations  are  telegraphed  to  the  central  office 
at  Washington.  There  they  are  examined,  and  it 
is  ascertained  what  they  indicate. 

A  storm  begins,  as  we  know,  within  or  near  an 
area  of  low  barometer.  Suppose  on  a  certain  day 
the  7  o'clock  observations  indicate  a  rapid  fall  of- 
the  mercury  at  Omaha,  St.  Louis,  and  Keokuk  ; 
while  to  the  eastward  and  westward  of  those  points 
the  barometer  stands  comparatively  high.  We 
know  that  a  storm,  from  the  Pacific  or  from  the 


Gulf,  has  entered  the  Mississippi  Valley  ;  we  also 
know  that  it  is  likely  to  make  its  way  to  the  east- 
ward. Moreover,  the  later  observations  of  the 
same  day  at  jwints  to  the  eastward  will  reveal  tlie 
direction  in  which  the  area  of  low  barometer  is 
travelling,  and  the  rate  of  its  movement.  Hence 
it  can  be  predicted  where  the  storm  is  likely  to 
strike,  and  when. 

This  illustrates  the  way  in  which  storms  are 
foretold.  On  the  approach  of  one,  cautionary  sig- 
nals are  displayed  at  the  lake  ports  and  at  those  of 
the  Atlantic  coast.  The  annual  saving  of  life 
and  property  due  to  these  warnings  is  immense. 

Changes  of  temperature  arc  foretold  on  the  same 
principle  as  storms.  The  Signal  Service  Bureau 
telegraphs  daily  information  as  to  weather  proba- 
bilities all  over  the  country,  and  by  its  maps  and 
bulletins  forewarns  us  of  approaching  wind  and 
rain,  frost  and  snow,  waves  of  heat  and  cold. 

TOPICAL   ANALYSIS. 
IV.    STORMS. 

1.  General  Description. 

Iliirriciiiics  and   toriiaiiocs,    Tyi)hoonp.    Cyclones. 

2.  Cause  of  Storms. 

(."ause  of  sjiii-al  movcnu-iit.     Jlliistration. 

3.  Laws  of  Storms. 

DiroctioTi  of  the  whirl.  Forward  motion  of  the 
storm.  Calm  at  the  centre.  Causes  of  low  ba- 
rometer at  centre.  Irregularity  of  land  storms. 
Storm  at  St  Thomas. 

4.  Value  of  Storm  Laws. 

5.  Area  of  Storms. 

6.  Whirlwinds  and  Tornadoes. 

Points  of  difference  between  these  and  hurricanes 
and  typhoons.  Destmctive  effects.  Dust  whirl- 
winds    Waterspouts 

7.  Distribution  of  Storms. 

8.  Weather  Forecasts. 

Great  stormif  of  the  United  States.    Prediction  of. 

Test  Questions.  —Is  there  any  relation  between  the  frequency  and 
power  of  storms  and  the  temperature  of  the  places  \\'here  they  occur  ? 
Why  do  they  form  more  sublime  spectacles  at  sea  than  on  land  ? 
When  the  earth  was  much  hotter  than  now,  what  must  have  been  the 
character  of  the  storms  ?    Why  ? 


V.  MOISTURE  OF  THE  AIR. 


h 


1.  Amount. — More  or  less  moisture  is  always 
present  in  the  air.  It  exists  in  the  form  of  vapor. 
Although  this  vapor  is  invisible,  we  can  form 
some  estimate  of  its  amount. 

The  rivers  measure  it  for  us.  For  the  same 
amount  of  water  that  they  discharge  has  heen 
taken  up  from  the  sea  in  the  form  of  vapor. 

The  general  law  regarding  tlie  amount  of  moist- 


86 


MOISTURE    OF    THE    AIR. 


uro  in  the  atmosphere  is,  that  the  warmer  the  air, 
the  more  moisture  it  can  contain. 

2.  JEvaporation. — One  of  the  most  wonder- 
ful of  the  many  wonderful  properties  of  water  is 
the  readiness  with  which  it  passes  from  one  of  its 
forms  to  another.  The  assuming  of  the  condition 
of  vapor  is  termed  evaporation. 

Evaporation  goes  on  at  all  temperatures  and 
under  all  circttrnstances. 

lllustraliuns. — You  may  have  observed  wa(er  drying  in 
our  streets  and  roads  after  a  rain,  or  clothes  lianging  on 
the  line  frozen  stiff,  and  yet  becoming  dry ;  or  you  may  hav(" 
seen  a  light  fall  of  snow  disappear  in  freezing  weather. 
These  were  all  cases  of  evaporation. 

Evaporation  is  accelerated  and  augmented  (1) 
by  high  temperature  ;  (2)  by  diminution  of  press- 
VLte  ;  (3)  by  a  dry  condition  of  the  atmosphere  ; 
(4)  by  wind. 

Effect  of  Temperature.  —  Tlie  higher  the 
temperature,  the  greater  and  more  rapid  ivill  evap- 
oration ie.  Hence  we  find  the  maximum  of 
evaporation  within  the  tropics ;  the  minimum  at 
the  poles.  Evaporation  talces  place  chiefly  through 
the  day,  and  in  the  warmest  ])art  of  the  day. 

Effect  of  Pressure. — The  less  the  atmospheric 
pressure,  the  more  rapid  zvill  evaporation  le.  In 
a  vacuum  there  is  almost  no  pressure,  and  tliere 
evaporation  takes  place  almost  instantaneously. 
Hence  on  the  tops  of  high  mountains,  where  the 
pressure  of  the  atmosjihere  is  very  much  dimin- 
ished, evaporation  goes  on  much  more  rapidly  than 
it  does  at  the  sea-level,  where  the  full  jiressure  of 
the  entire  atmosphere  is  felt. 

Indeed  mountain  peaks  may  be  so  high  as  to  be 
entirely  free  from  snow,  while  a  belt  of  snow  gir- 
dles the  lower  part  of  the  mountain.  Tlie  reason 
of  this  appears  to  be  that  at  certain  altitudes 
snow  evajiorates  so  rapidly  that  it  cannot  accu- 
mulate. 

Aconcagua  in  Chili  sometimes  appears  with  its 
bare  and  bleak  top  peering  above  a  girdle  of  snow. 

Effect  of  Dryness. — Atmospheric  air  can 
absorb  or  take  up  a  certain  amount  of  moisture. 
Warm  and  dry  air  will  absorb  far  more  than  cool 
and  damp.  When  air  has  absorbed  all  the  moist- 
ure that  it  can  retain,  it  is  said  to  be  saturated. 
Now  if  the  air  be  near  the  point  of  saturation,  it 
is  clear  that  evaporation  will  be  retarded,  while 
again  if  tlie  air  is  dry,  it  will  be  encouraged. 

In  a  damp  foggy  atmosphere  you  see  every 
breath  that  you  discharge.  The  air  has  all  the 
moisture  that  it  can  contain,  and  has  no  absorptive 
capacity.  In  a  dry  warm  air  your  breath  is  invis- 
ible. It  is  absorbed  as  soon  as  it  leaves  your 
mouth. 


Effect  of  Wind. — If  a  wind  blow  upon  the 

surface  of  water,  evaporation  is  accelerated.  This 
is  because  as  fast  as  one  portion  of  tlic  air  becomes 
charged  with  vajjor,  it  is  removed,  and  a  fresh  por- 
tion takes  its  place. 

.*?.  ('ondcufiation  and  Precipitation. 

— Vapor  returns  to  the  liquid  or  solid  state  and  is 
deposited  upon  the  earth  by  the  processes  called 
condensation  and  precipitation. 

When  condensed,  it  assumes  the  form  of  dew, 
white  or  hoar-frost,  fog  or  cloud,  hail  or  snow. 

The  great  cause  of  precijntation,  or  the  removal 
of  moisture  from  the  atmosphere,  is  loss  of  heat. 
The  atmosphere  can  contain  more  or  less  vapor  in 
a  state  of  absorption  in  proportion  to  its  tempera- 
ture. If  tlie  temperature  be  50°  Fahr.  a  cubic 
foot  of  air  can  absorb  about  2  grains'  weight  of 
vapor.  At  the  temperature  of  70°  Fahr.,  i.e.,  with 
an  increase  of  only  20°  of  heat,  the  proportion  of 
vapor  is  about  twice  as  great. 

From  this  it  is  easy  to  see  why  reduction  of 
temiicrature  causes  precipitation.  Suppose  a  cubic 
foot  of  air  saturated  with  moisture  to  be  reduced 
in  temperature,  even  very  slightly  ;  it  is  obvious 
that  its  capacity  for  moisture  will  be  at  once  re- 
duced, and  a  certain  portion  of  its  vapor  must  be 
precipitated.  The  temperature  at  which  the 
deposit  in  such  cases  begins  to  take  place,  is  called 
the  deio-point. 

4.  How  Dew  *.s  Formed. — On  clear  and 
calm  nights,  the  grass,  the  leaves,  and  other  ob- 
jects rapidly  radiate  their  heat  and  gi-ow  cool. 
They  chill  the  surrounding  air.  It  can  no  longer 
contain  the  same  amount  of  moisture  as  when  it 
was  warm.  Hence  a  portion  of  it  is  condensed 
and  deposited  upon  the  leaves  in  the  shape  of  fine 
drops  of  water.  We  often  say  "  the  dew  begins  to 
fall,"  though,  strictly  speaking,  it  does  not  fall. 
It  is  deposited  iipon  the  grass  precisely  as,  on  a 
hot  summer's  day,  the  moisture  is  deposited  on 
the  outside  of  a  pitcher  of  ice  water. 

Clouds  check  radiation,  and  hence  on  cloudy 
nights  less  dew,  or  perhaps  none  at  all,  is 
deposited. 

You  must  have  noticed  that  dew,  and  hoar- 
frost, which  is  only  frozen  dew,  are  deposited  on 
some  objects  more  copiously  than  others.  This  is 
because  some  radiate  heat  more  rapidly,  and  there- 
fore chill  and  condense  more  quickly  the  vapor  of 
the  air  that  rests  above  them. 

5.  Foff. — Vapor  coming  in  contact  with  cool 
air,  if  chilled  below  the  dew-point,  becomes  vis- 
ible. It  assumes  the  form  of  fine  wateiy  parti- 
cles which  we  call  mist  or  fog. 


MOISTURE    OF    THE    AIR. 


87 


Illustrations. — The  condensation  of  your  breath 
into  mist,  as  it  passes  from  your  mouth  into  tlie 
cold  air,  is  a  familiar  illustration  of  this. 

You  may  also  have  observed  tliat  in  a  clear, 
calm,  and  frosty  morning  the  springs,  ponds, 
and  rivers  "smoke."  This  is  the  same  phe- 
nomenon that  is  exhibited  by  the  steam  which 
issues  from  the  tea-kettle,  the  locomotive,  and  the 
steamboat. 

Very  often,  too,  fogs  are  seen  upon  the  surface 
of  rivers  in  the  early  morning.  Toward  noon  they 
vanish.  The  morning  aii',  because  cool,  cannot 
retain  so  much  moisture  in  absorption,  but  when 
tiie  rays  of  the  sun  have  warmed  it,  and  increased 
its  capacity  for  moisture,  it  absorbs  the  vapor,  and 
the'  fog  disap- 
pears. 

T%e  most  foggy 
sea  in  the  world 
is  that  part  of 
the  Nprth  At- 
lantic Ocean 
that  lies  on  the 
polar  side  of  lat- 
itude 40' ;  and 
the  most  foggy 
place  is  on  the 
Grand  Banks  of 
Newfoundland. 

Vapor  rises 
rapidly  from  the 
warm  water  of 
the  Gulf  Stream 
near  the  Grand 
Banks.  It  is  met 
there  by  the  cold 
current  from  the 
north.  Owing  to 
the  chilling  in- 
fluence of  this 
current  the  va- 
por is  condensed 
into  fog  as  fast 
as  it  rises. 

Though  fogs  are  most  frequent  in  summer,  they  occur 
on  the  Grand  Biinks  at  all  seasons,  producing  in  winter  the 
exquisitely  beautiful  silver  fogs  of  Newfoundland,  which 
garnish  the  forests  of  that  island  with  frostwork. 

(i.  Clouds. — A  cloud  is  simply  a  mass  of  mist 
or  fog  floating  high  in  the  air  instead  of  near  the 
ground. 

Clouds  present  a  very  great  variety  of  appear- 
ance, and  hence  are  divided  into  seven  classes  : 
three  simple,  cirrns,  cinniihis,  and  stratus  ;  four 
compound,  cirro-cumulus,  cirro-stratns,  ciiniulo- 
stratus,  and  ciimulo-cirro-sfratus  or  nhnbus. 

Cirrus. — The  cirrus  or  curl  cloud  consists  of 
white  wavy  lines  or  curled  bands.  It  is  the  light- 
est of  all  cloud-forms,  and  attains  the  highest  ele- 
vations, floating  four  or  five  miles  above  the  --ur- 


KUliMS  OF   CLOUDS 


1.  Cirrus. 

2.  Cumulus. 


face  of  the  earth  in  regions  of  perpetual  frost.  It 
is  supposed  to  consist  of  minute  crystals  of  ice 
such  as  we  see  in  the  snowflakc,  and  may  be  de- 
fined as  frozen  fog. 

Cirrus  clouds  are  often  heralds  of  the  cyclone.  Only  re- 
cently these  nimble  forerunners  were  observed  800  miles  in 
advance  of  a  storm  thiit  swept  over  England.  They  some- 
times caution  the  mariner,  ere  his  barometer  gives  any  in- 
timation of  the  approaching  tempest. 

Cumulus  clouds  derive  their  name  from  the  fact 
that  they  are  heaped  up,  like  vast  mountains  tower- 
ing one  upon  another.  They  are  often  of  glisten- 
ing whiteness.  They  abound  in  the  tropics,  and 
frequently  appear  in  the  sky  of  temperate  latitudes 
during  the  summer,  when  evaporation  is  rapid. 

Of  all  cloud- 
forms  they  are 
perhaps  the 
grandest.  Out 
of  them  darts 
the  lightning 
which  makes 
our  thunder- 
storms  so 
magnificent. 

Stratus 
clouds  appear 
in  the  shape 
of  long  layers 
or  ribbons. 
They  are  seen 
most  f  r  e  - 
quently  in  the 
evening,  and, 
when  tinged 
by  the  rays  of 
t  h  e  setting 
sun, they  form 
those  islets  of 
gold  which 
render  the  sunset  sky  so  beautiful. 

The  compound  clouds  combine  the  features  of 
the  simple  ones  from  which  they  are  named. 

The  Cirro-cumulus  is  made  up  of  fleecy  masses 
of  cirrus  which  roll  themselves  up  into  rounded 
shapes.  These  cause  the  mottled  appearance  com- 
monly known  as  a  "  mackerel  sky." 

The  Cirro-stratus  consists  of  layers  of  cirrus 
clouds.  They  are  often  so  arranged  as  to  resem- 
ble a  shoal  of  fishes,  all  swimming  parallel  to  one 
another.  This  cloud,  like  the  cirrus,  is  often  the 
jirecursor  of  storms. 

The  Cumulo-stratus  is  formed  of  heajjed 
clouds  resting  on  layer  clouds.  Like  the  cumulus, 
its  general  mass  is  often  cpiite  dark  and  threateu- 


3.  Stratus. 

4.  Nimbus. 


MOISTURE    OF   THE    AIR. 


ing,  while  its  edges  arc  bright  with  sunshine  that 
is  behind  the  clouds. 

The  Cumulo-cirro-stkatus,  or  nimbus,  is 
sim^jly  a  cloud  of  any  kind  from  wliich  rain  falls. 
Heaped  clouds,  and  curls  and  layers  blend  to- 
gether, lose  their  characteristic  features,  and  form 
one  dense  leaden  mass.  It  often  overspreads  the 
whole  heavens. 

Velocity. — The  velocity  of  cloud  movement, 
when  accurately  estimated  by  observers,  is  found 
to  be  far  more  rajjid  than  we  should  suppose  from 
the  apparent  rate  of  the  "passing  cloud."  It  has 
been  found  that  cumulus  clouds  which  seem  to  be 
moving  at  a  leisurely  rate  are  often  travelling  75  to 
100  miles  an  hour. 

This  is  of  very  great  interest,  for  it  indicates  to 
us  the  velocity  of  the  upper  currents  of  the  at- 
mosphere. 

Height  of  Clouds. — Wlien  clouds  rest  on  the 
tops  of  mountains,  they  are  actually  in  contact 
with  the  earth  ;  often  indeed  they  are  below  the 
summit  of  the  mountain.  Their  average  eleva- 
tion, however,  is  about  half  a  mile.  At  times  they 
cannot  bo  less  than  four  or  five  miles  high. 

Why  the  Clouds  do  not  fall. —Clouds  are  not  vapor; 
they  consist  either  of  minute  vesicles — that  is,  tiny  hollow- 
globes  of  water — or  of  fine  ice-crystals.  In  either  case  they 
are  mucli  heavier  than  air.  Why,  then,  do  they  not  fall  ? 
So  far  as  we  know,  they  are  falling  constantly.  But  the 
lower  part  of  the  cloud,  as  it  comes  into  warmer  air,  is  dis- 
solved again  to  vapor,  and  disappears,  while  a  new  portion 
may  at  the  same  time  be  formed  above.  Thus  the  cloud, 
though  constantly  sinking,  retains  its  place. 

A  different  view  is  proposed  in  a  recent  theory.  It  is 
that  clouds  consist  of  minute  watery  particles  which  have 
attached  themselves  to  motes  floating  in  the  atmosphere, 
and  that  these  buoy  them  up. 

Offices  of  Clouds. — The  main  offices  of  clouds 
are  two  :  (1)  they  screen  the  earth  from  excessive 
heat  in  summer,  while  in  winter  they  are  a  mantle 
to  keep  it  warm  by  checking  radiation. 

Plants  and  animals  are  distressed  by  the  intense  heat  of 
the  noonday  sun.  But  the  more  powerful  the  ray,  the  more 
rapid  is  evaporation.  Soon  vaj5or  enough  is  lifted  from  the 
earth  to  form  the  mitigating  clouds.  They  overshadow  the 
land,  and  both  plants  and  animals  are  protected  from  the 
fierce  and  scorching  sun. 

(2)  they  enhance  the  beauty  of  the  natural 
world.  A  pure  blue  sky,  unvaried  day  after  day 
by  a  cloud,  is  not  to  be  compared  with  one  in 
which  azure  and  white  are  contrasted.  Nothing 
is  more  missed  by  the  traveller  in  Egypt  than  the 
grandeur  of  our  storm  clouds  and  the  varied 
beauty  of  our  evening  skies. 

7.  Rain. — The  first  form  assumed  by  the 
moisture  of  the  upper  air  when  condensed  is  that 


of  cloud.*  If,  however,  the  process  of  condensa- 
tion continue,  and  vapor  exist  in  almndance,  it  is 
easy  to  see  that  the  tiny  water  particles  which 
make  up  the  cloud  will  increase  in  size,  until  they 
are  too  heavy  to  float,  and  will  fall  as  raindrops  to 
the  earth. 

The  general  cause  of  rainfall  is  that  a  certain 
volume  of  vapor-laden  air  has  been  chilled  below 
the  dctv-]}oint,  so  that  it  has  no  longer  the  same 
capacity  for  moisture  as  before.  This  may  be 
brought  about  in  several  ways  :  (1)  the  moist  air 
may  be  driven  up  a  lofty  mountain  slope  into  the 
higher  and  colder  regions  of  the  atmosphere  ;  (2) 
it  may  be  carried  thither  as  an  ascending  current 
of  heated  air ;  (3)  it  may  be  chilled  by  being 
mixed  with  a  mass  of  colder  air  ;  (4)  a  change  in 
the  electrical  condition  of  the  air  appears,  in  some 
unknown  way,  to  reduce  the  capacity  of  the  at- 
mosphere for  moisture.  This  last  is  often  ob- 
served in  a  thunder-storm,  when  vivid  discharges 
of  lightning  are  followed  by  an  immediate  increase 
in  the  downfall  of  rain. 

S.  Distrihutiou  of  Rain.—^&m  is  very 
unequally  distributed  over  the  earth. 

(1)  The  rainfall  is  greater  on  land  than  at  sea. 

(2)  It  is  greater  in  mountainous  than  in  level 
regions. 

The  reason  of  both  these  facts  is,  that  elevations 
have  tlie  effect  of  directing  vapor-laden  air  into 
the  higher,  cooler  regions  of  the  atmosphere. 

(3)  The  rainfall  is  greater  in  the  torrid  than  in 
any  other  zone.  The  average  annual  quantity  at 
the  equator  is  eight  feet.  It  diminislies  as  we  ap- 
proach the  poles.  This  follows  from  the  fact  that 
the  torrid  zone,  being  the  hottest,  is  that  of  the 
greatest  evaporation. 

While,  however,  these  are  the  general  facts  re- 
garding the  distribution  of  rain,  there  are  modify- 
ing causes  which  exert  a  very  important  influence. 

.9.  Befjulators  of  Rainf all. —The  great 
regulators  of  the  rainfall  are  the  mountain  chains, 
the  deserts,  and  the  winds.  Each  of  these  has  an 
important  part  to  perform  in  distributing  the  rain 
over  the  surface  of  the  earth. 

Influence  of  Mountains. — The  mountains 
are  the  great  condensers  of  vajior.  If  mountain 
chains  face  the  winds  that  come  from  the  sea,  they 
render  the  region  between  themselves  and  the  sea 
a  well-watered  one.  They  not  unfrequently  make 
rainless  the  region  beyond  them.  They  rob  the 
winds  of  their  moisture. 


*  Rain  sometime?  falls  from  a  cloudless  sky.  In  such  cases  vapor  Is 
condciii^cd  directly  into  water,  without  passing  through  the  inten'ening 
stage  of  cloud. 


MOISTURE    OF   THE   AIR 


89 


In  India. — Thus  the  Himalayas  face  the 
southwest  monsoon,  as  it  comes  freiglited 
with  vapor  from  the  Indian  Ocean.  They 
make  India  one  of  the  most  jiroductive 
countries  in  the  world  ;  but  the  jjlatcaus 
lying  to  the  north  of  ihcni  are  almost  rain- 
less. On  a  smaller  scale  the  Western 
Ghauts  act  in  the  same  way.  They,  too, 
lie  in  tlie  ])athway  of  the  monsoons,  and 
intercept  and  condense  (heir  vapors.  The 
annual  I'ainfall  ujjon  their  tops  amounts  to 
about  260  inches,  while  the  country  on  the 
east  of  them  receives  comparatively  little 
rain. 

But  perhai^s  the  most  striking  illustra- 
tion of  the  influence  of  mountains  upon 
rainfall  is  to  be  found  in  the  case  of  the 
Khasia  hills,  on  the  northern  shores  of  the 
Bay  of  Bengal.  They  intercept  tlie  south- 
west monsoons,  as  they  come  burdened  with 
vapor  from  the  bay.  The  result  is  that  the 
winds,  as  they  slant  up  the  hills  into  the 
higher  and  cooler  air,  have  their  moisture 
at  once  precipitated  as  rain,  of  which 
nearly  600  inches  fall  there  in  the  year. 

In  South  America  tiie  influence  of  the 
Andes  is  familiar.  The  northeast  and 
southeast  trades  come  from  the  sea  satu- 
rated with  vapor,  and  so  go  into  the  inte- 
rior, rising,  and  cooling,  and  dispensing 
showers  as  they  go,  until  they  reach  the 
crest  of  the  Andes.  Here  the  cold  is  suf- 
ficient to  squeeze  almost  all  the  remaining 
moisture  from  them.  Thus  the  easttru 
side  of  these  mountains,  within  the  trade- 
wind  region  [see  Chart  of  the  Winds],  is 
abundantly  watered,  while  the  western  is 
dry.  Hence  it  is  that  Peru  is  a  rainless 
country. 

South  of  the  mouth  of  the  La  Plata,  the 
reverse  takes  place.  There  the  prevailing 
winds  are  from  the  west.  They  come  from 
the  Pacific,  reeking  with  moisture,  and . 
water  the  western  slojjes  of  the  Andes, 
causing  the  excessive  rains  of  Southern 
Chili.     The  eastern  slopes  are  comparatively  dry. 

In  our  own  country  the  Cascade  Eange  and  the 
Sierra  Nevada  have  a  similar  influence.  They  lie 
in  the  pathway  of  the  westerly  winds  which  come 
loaded  with  moisture  from  the  Pacific.  They  act 
as  condensers,  and  bring  down  the  copious  show- 
ers which  give  fertility  to  the  Pacific  slope. 

Influence  of  Deseets. — In  many,  cases  the 
deserts  are  the  directors  of  the  winds,  and  thus 
become  regulators  of  the  rainfall. 


VIEW    OF   THE    AT-MO-niERE    T^UKING    A    RAIX-STOKM. 

India  is  in  a  region  in  wliich  the  northeast 
trade  winds  blow  over  the  land,  and  are  rainless. 
Were  it  not  for  the  deserts  of  Central  Asia,  which 
have  the  effect  of  drawing  in  the  southwest  mon- 
soons [see  p.  80],  India  would  be  as  arid  as  Gobi. 

In  Africa  the  Sahara  produces  the  monsoons 
which  blow  from  the  Indian  Ocean  upon  that  con- 
tinent. By  the  month  of  June,  the  desert  is 
heated  up  sufficiently  to  bring  in  the  sea  winds. 
The  rainy  season  then  begins,  and  lasts  till  late 
in  autumn. 


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Questions  on  the  Rain  CnA3T. 

How  is  the  larger  or  smaller  amount  of  annual  rainfall 
indicated  on  the  chart  ?  How  are  monsoons  indicated  ? 
Where  is  the  district  of  tlie  great  monsoons  ?  What 
portion  of  the  earth's  surface  has  the  greatest  annual 
rainfall  ?    What  winds  bring  the  rains  to  this  region  ? 


Eif'-ml  ,t.,-fn6^-j  ''■,-/tV 


Trace  the  northern  and  southern  limits  within  which 
snow  does  not  fall  at  the  level  of  the  sea.  (The  two  red 
lines  crossing  the  chart  indicate  the  northern  and  south- 
em  boundaries  of  the  periodical  rains.)  Within  these 
boundaries  how  is  the  year  divided  ? 

Where  is  the  belt  of  constant  rains  ?  By  what  phe- 
nomenon are  these  rains  usually  accompanied  ?  / 


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RAIN  CHART, 

^lioumu  111.' 

y/u   .}.irhr  lhr  .shading  the.  ffnutt,^ is-  fhf  Ycarh/  Am.'imr 
,<r  Slum  and  Tiniji  /■*///. 

,  Frrvtih'nt/    Winds. 

Mtmsoorw--.  ~"" 

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rf  ffr.-  iVfi'V    -t'  lhr  /lAr.i/ 


What    parts  of    North    America   have   the   greatest 
nnual  rainfall  ?    What  countries  of  South  America  ? 
Vhat  countries  on  the  east  and  west  shores  of  Africa  ? 
Vhat  portions  of  Asia  ?    Of  Australia  ? 
"At  what  seasons  are  the  rains  of  Europe  most  frequent  ? 

In  what  parts  of  North  America  do  spring  and  sum- 
ler  rains  prevail  ?    Where  do  all-the-year  rains  prevail? 


■5.l^^^  Vn  Wv-.rr  J  SmiCTT^  ,"8  ■ 


Where  autumnal  and  winter  rains  ?     Summer  rains  ? 

What  parts  of  what  countries  are  embraced  within  the 
range  of  the  Equatorial  Calms  and  Cloud-ring  ? 

What  rainless  districts  are  indicated  ?  Can  you  ex- 
plain why  these  districts  are  rainless  ? 

What  places  in  the  United  States  have  the  heaviest 
rainfall  ?    (See  Table  on  last  page  of  the  book.) 


92 


MOISTURK    OF   T^E    AIR. 


The  periodical  overflow  of  the  Nile  is  due  to 
the  rains  into  whicli  the  vajror  is  condensed  wliich 
the  African  monsoons  bring  with  them  from  the 
sea.  Thus  Egypt  owes  its  fertility  in  some  degree 
to  tlie  burning  sands  of  Sahara. 

North  America  lias  its  deserts  and  its  monsoons, 
though  they  are  far  less  marked  tlian  those  of  the 
Old  World. 

The  table-lands  of  Mexico,  Arizona,  the  dry  plains  of 
Texas,  New  Mexico,  and  the  neighboring  regions,  are 
heated  by  the  summer  sun  to  such  a  degree,  that  the  air 
resting  upon  them  becomes  rarefied,  and  ascends,  the  cooler 
air  from  far  and  near  coming  in  to  restore  the  equilibrium. 
Thus  a  southeast  monsoon  is  created  in  tlii!  Gulf  of  Mexico, 
and  a  southwest  one  in  the  Pacific. 

Both  of  these  winds  blow  toward  the  land,  and  bring  the 
rains  to  Mexico,  so  that  one  side  of  that  country  is  watered 
from  the  Pacific,  tlie  otlier  from  the  Atlantic  Ocean. 

Influence  of  the  Winds. — As  a  general  rule 
winds  are  dry,  if  they  have  traversed  the  land,  or  if 
they  are  journeying  toward  the  equator.  Winds 
are  wet,  if  they  have  traversed  the  sea,  or  if  they 
are  journeying  from  the  equator. 

Dry  Winds. — Land  winds  are  dry  for  the  sim- 
ple reason  tliat  they  have  so  little  opportunity  to 
take  up  moisture.  Thus  the  northeast  monsoons 
which  sweep  over  the  inland  regions  of  Asia  are 
the  dry  monsoons.  The  westerly  winds  of  our 
own  country,  all  the  way  from  the  Sierra  Nevada 
to  the  Atlantic,  are  dry  winds.  They  bring  our 
fair  weather. 

Again  :  a  wind  that  is  blowing  toward  the 
equator  is  dry,  because,  entering  warmer  latitudes, 
it  is  gaining  capacity  for  moisture  with  every  dc- 
gi'ee  of  its  progress.  The  trade  winds,  for  ex- 
ample, blow  toward  the  equator.  You  perceive, 
therefore,  that  they  are  going  from  cooler  to 
warmer  latitudes.  Their  temperature  is  increased 
by  the  way,  and  with  increase  of  temperature 
there  is  increase  of  capacity  for  moisture.  The 
trade  winds,  therefore,  take  up  more  water  from 
tlie  sea  than  they  return  to  it.  They  are  evapo- 
rating winds. 

Wet  Winds. — Sea  winds  and  winds  blowing 
toward  the  poles  are  rainy.  The  counter  trades 
go  toward  the  poles.  They  are  travelling  from 
warmer  to  cooler  latitudes.  Their  temperature  is 
decreased  by  the  way,  and,  therefore,  there  is  a 
decrease  in  their  cajjacity  for  moisture  ;  they  de- 
posit more  than  they  take  up.  They  are,  there- 
fore, rain  winds. 

10.  Bains  Classified.— The  winds  are 
classified  according  to  the  regularity  with  which 
they  blow,  as  constant,  variable,  and  periodical. 
It  is  proper,  therefore,  to  classify  the  rains  which 
they  bring  in  the  same  way.     Hence,  according  to 


the  nature  of  the  supplying  winds,  the  rainfall  in 
any  given  region  is  Constant,  Periodical,  or  Vari- 
able. 

Constant  Eains. — The  constant  rains  are 
confined  to  a  belt  near  the  equat(jr,  about  5°  wide. 
In  this  belt  there  are  almost  daily  sliowers.  The 
cause  is  clear. 

The  northeast  and  southeast  trades  meet  near 
the  equator.  They  are  so  completely  saturated 
with  moisture  that  the  sailor,  hanging  out  his 
clothes  ill  the  morning,  is  often  surprised  to  find 
in  the  evening  that  they  have  not  dried  in  tlie 
least.  Under  tlic  vertical  rays  of  the  sun  an  as- 
cending current  is  produced  which  carries  the 
vapor-laden  air  into  the  higher  regions  of  the 
atmosphere.  Here  tlio  vapor  is  cooled  and  con- 
densed ;  and  hence  the  frequent  thunder  showers 
of  this  region  of  constant  precipitation. 

y\  Periodical  Rains. — Witliin  the  tropics,  to  the 
north  and  to  the  south  of  the  narrow  belt  of  Con- 
stant Eains,  lie  the  belts  of  Periodical  Rains. 

In  the  Xeio  World  the  jjeriodical  rainfall  is 
closely  connected  with  the  annual  movement  of 
the  Equatorial  Calm  Belt  and  its  accompanying 
Cloud  Ring. 

The  Calm  Belt  travels  northward  and  south- 
ward, following  the  annual  movement  of  the  sun 
in  the  heavens.  It  is  farthest  south  in  March, 
and  fartiiest  north  in  September. 

During  the  time  that  it  is  passing  over  a  place, 
it  gives  to  that  place  its  rainy  season.  After  it 
has  passed,  there  is  scarcely  a  drop  of  rain  until  it 
comes  again. 

Let  us  follow  the  cloud  ring  in  its  journey  from  south  to 
north,  and  you  will  readily  understand  its  movements,  and 
the  rainy  seasons  that  depend  upon  them. 

The  time  is  February;  it  is  then  over  Guayaquil  (lat.  3' 
S.),  and  then  the  rainy  season  there  is  at  its  height.  It  com- 
mences its  movement  for  the  north  in  March.  Quitting  the 
skies  of  Guayaquil  soon  after,  it  leaves  them  bright  and 
clear  with  the  commencement  of  the  dry  season.  In  a  little 
while  it  has  travelled  as  far  as  latitude  4'  N.  It  then  over- 
shadows Bogota,  where  the  rains  begin  in  April  or  May. 
In  June  it  is  over  Panama,  and  hence  a  rainy  season  pre- 
vails there;  and  so  the  cloud  ring  continues  on  to  Mexico, 
reaching  Mazatlan,  just  under  the  tropic,  about  September, 
when  it  commences  its  march  toward  the  south,  so  as  to  be 
again  at  Guayaquil  by  February  or  March. 

It  is  clear  that  on  its  return  from  north  to  south  the 
cloud  ring  must  give  to  certain  places  a  second  rainy  season, 
because,  in  coming  and  going,  it  passes  over  them  twice. 

In  the  Old  World  the  periodical  rains  are  occa- 
sioned by  the  monsoons  or  reversed  trades.  For 
about  six  months,  in  Southern  Asia  and  Central 
Africa,  copious  rains  fall.  When  the  monsoons 
cliange,  the  dry  season  sets  in,  and  scarcely  any 
rain  falls  until  after  six  months,  when  the  wet 
monsoon  begins  to  blow  again. 


MOISTURE    OF    THE    AIR. 


93 


Rainy  and  Dry  Seasons. — Within  the  belt  of 
the  Periodical  Rains  the  year  is  divided  into  rainy 
seasons  and  dry. 

In  general  tci'ins,  the  rainy  season  in  the  northern  belt 
may  be  said  to  begin  with  April,  and  last  till  October,  while 
the  dry  season  extends  from  October  till  April.  In  the 
southern  belt  this  order  is  reversed — the  dry  season  lasting 
from  April  till  October,  and  the  season  of  rain  from  Octo- 
ber till  April. 

It  is  not  to  be  supposed  that  during  the  rainy  season 
there  is  an  incessant  fall  of  rain.  In  Mexico,  for  instance, 
the  rainy  season  is  the  most  delightful  portion  of  the  year. 
As  a  nde,  the  nights  and  mornings  are  clear  and  beautiful, 
and  the  weather  fine,  with  a  few  hours  of  rain  after  three 
or  four  o'clock  p.  m. 

Variable  Eains.— North  and  south  of  the 
belts  of  Periodical  Rains,  the  rains  become  Varia- 
ble ;  i.e.,  they  are  irregularly  distributed  through 
the  year.  In  some  countries  they  occur  nuiinly 
during  the  summer,  in  others  during  the  winter ; 
in  others,  again,  during  the  spring  and  autumn. 
This  condition  of  things  prevails  throughout  the 
temperate  regions. 

11.  Excessive  and  Deficient  Rain- 
fall.— Owing  to  the  influence  of  local  causes, 
there  are  regions  of  excessive  and  deficient  rain- 
fall. Let  the  pupil,  now  familiar  with  the  influ- 
ence of  the  winds,  the  mountains,  and  the  deserts, 
refer  either  the  excess  or  the  deficiency  in  the 
cases  about  to  be  mentioned  to  its  appropriate 
cause.     [See  Rain  Chart.] 

Regions  of  Excess. — Naturally  the  regions  of 
excessive  rainfall,  with  few  exceptions,  lie  within 
or  near  the  tropics.  Cherrapunjee,  in  the  vicinity 
of  the  Khasia  hills  in  India,  receives  annually 
about  600  inches — or  a  depth  of  fifty  feet — a  greater 
amount,  so  far  as  we  know,  than  any  other  place 
on  the  globe. 

Parts  of  the  British  Isles,  the  coasts  of  Guinea  and  Sene- 
gambia,  Eastern  Africa  and  India,  are  all  remarkable  for 
their  heavy  rainfall. 

In  the  New  World,  Brazil,  Guiana,  Venezuela,  the  West 
India  Islands,  Central  America,  Patagonia  and  the  Pacific 
shores  of  Alaska  are  all  regions  of  excessive  rainfall. 

Regions  op  Deficiency^ — Rainless  or  almost 
rainless  regions  are  the  great  belt  of  deserts  ex- 
tending across  Africa  and  Asia,  from  the  Atlantic 
nearly  to  the  Pacific  ;  the  Great  Basin  in  Nortli 
America,  lying  eastward  of  the  Sierra  Nevada  ; 
Peru,  together  with  the  northern  part  of  Chili, 
and  portions  of  the  Argentine  Republic  lying 
eastward  of  the  Andes. 

Cultivation  in  all  dry  coimtries  is  carried  on  by  means  of 
irrigation.  For  this  purpose  tanks  have  been  constructed 
in  India  at  vast  expense.  The  Peruvian  farmers  avail 
themselves  of  the   mountain-streams  that  ai-e  fed  bv  the 


snows  of  the  Andes  ;  while  the  peasant  of  Egypt,  like  his 
ancient  forefathers,  supplies  his  fields  and  his  gardens  from 
the  sacred  waters  of  the  Nile. 


TOPICAL    ANALYSIS. 
V.    MOISTURE   OK   TUE   AIR. 

1.  Amount. 

IIuw  measured. 

2.  Evaporation. 

Conditions  under  which  it  takes  place.  Causes 
which  increase  it.  Effect  of  temperature.  Con. 
sequent  place  and  time  of  maximum  evaporation. 
Effect  of  pressure.  Effect  of  dryness.  Effect  of 
winds. 

3.  Condensation  and  Precipitation. 

Cause  of  precipitation.  Dew-point.  Forms  of 
water  derived  from  vapor. 

4.  How  Dew  is  Formed. 

Effect  of  clouds.    Difference  in  quantity  of  dew  or 


5.  Fog. 


frost  formed  on  various  substances. 


How  formed.    Illustrations.     Fogs  of  the  Grand 
Banks. 


6.  Clouds. 

Various  forms.  Cirrus.  Cumulus.  Stratus.  Cirro- 
cumulus,  cirro-stratus.  Cumulo-stratus.  Cu- 
raulo-cirro-stratus.  Velocity  of  cloud  movement. 
Height  of  clouds.  Why  the  clouds  do  not  fall. 
Offices  of  clouds. 

7.  Rain, 

General  cause.    How  brought  about. 

8.  Distribution  of  Rain. 

n<)\v  chuslmI. 

9.  Regulators  of  Rainfall. 

Influence  of  mountains.  The  Himalayas.  Western 
Ghauts.  Khasia  hills.  The  Andes.  The  Cas- 
cade Range  and  Sierra  Nevada.  Influence  of 
deserts.  Deserts  of  Central  Asia.  The  Sahara. 
Tablelands  and  dry  plains  of  Mexico  and  the  ad- 
joining regions  of  the  United  States.  The  influ 
ence  of  the  winds.    Dry  winds.    Wet  winds. 

10.  Rains  Classified. 

Constant  rains.  Their  locality.  Cause.  Periodical 
rains.  Their  locality.  Annual  movement  of  the 
Equiitorial  Calm  Belt.  Periodical  rains  in  the 
Old  World.  Cause.  Rainy  and  dry  seasons. 
Variable  rains,  locality  of. 

11.  Excessive  and  Deficient  Rainfall. 

Regions  of  excess.  Of  deficiency.  Causes.  Irri- 
gation in  dry  regions. 

Test  Questions. — Dews  are  heavier  in  the  fall  than  in  spring ; 
why  ?  Why  are  they  heavier  on  low  grounds  than  on  the  adjacent 
hills  ?  You  have  noticed  that  the  clouds  in  spring  take  on  a  different 
appearance  from  what  they  have  in  winter  ;  can  you  think  of  any  rea- 
son for  it  ?  To  which  class  do  tluindiT-clouds  belong  ?  How  is  it  that 
clouds  change  their  forms  so  constantly  ?  Why  should  there  be  more 
rain  on  land  than  at  sea  ? 


94 


HAIL,  SNOW,  AND    GLACIERS. 


VL  HAIL,  SNOW,  AND  GLAGIEES. 

1.  Hall. — Moisture,  descending  through  tlie 
cold  upper  regions  of  the  atmosphere,  is  some- 
times frozen,  and  becomes  hail  or  snow. 

When  examined  carefully,  hail  has  been  found 
to  consist  of  concentric  layers  of  ice,  encasing 
one  another  like  the  layers  of  an  onion. 

In  size,  hailstones  vary.  Occasionally  they  are 
as  large  as  marbles,  .or  even  hens'  eggs,  so  that 
severe  hailstorms  occasion  very  great  damage  to 
crops. 

The  formation  of  hail  is  not  well  understood. 
It  usually  falls  in  the  heat  of  summer,  and  it  is 
difficult  to  account  for  a  temperature  at  that  sea- 
son so  low  as  to  freeze  the  moisture  of  the  atmos- 
phere. The  sudden  ascent  of  moist  air  into  the 
cold  upper  regions  of  the  atmosphere  is,  probably, 
the  most  common  cause  of  this  phenomenon. 


SNOW  CRYSTA1.S. 


V.  Show. — The  moisture  that  falls  from  the 
clouds,  frozen  in  flakes,  is  called  snow.  When  ex- 
amined, it  is  usually  found  to  consist  of  exquisitely 
formed  crystals,  which  are  generally  in  the  shape 
of  a  six-pointed  star.     [See  illustration.  J 

Snow  rarely  occurs  within  the  limits  of  about 
30°  north  and  south  latitude,  except  on  high 
mountain  tops.  It  is  naturally  more  abundant  as 
we  approach  the  poles.  It  is  also  in  general  more 
abundant  where  the  climate  is  inland,  than  where 
it  is  maritime.  Paris  has,  on  an  average,  12 
snowy  days  in  the  year  ;  St.  Petersburg,  170. 

Snotv  is  perpetual,  however,  even  at  the  equa- 
tor, upon  all  heights  greater  than  about  3  miles 
above  the  sea- level.  The  line  above  which  snow  is 
always  found  is  called  the  snow-line.  [See  small 
map  on  p.  10.5.]  It  varies  in  altitude  from  many 
causes. 

Whatever  tends  to  elevate  the  temperature  of 
any  locality,  tends  also  to  elevate  the  snow-line. 
Hence  a  low  snow-line  means  a  cold  climate. 
While  at  the  equator  the  snow-line  is  16,000  feet 
high,  at  the  Straits  of  Magellan  it  is  only  about 
4,000. 


The  Offices  of  Snow  are  two-fold  :  (1)  it 
protects  the  earth  and  the  crops  ])lanted  in  late 
autumn  from  the  intense  cold  and  the  injurious 
effects  of  frost.  Sometimes  there  is  a  difference 
of  40°  between  the  temjjerature  of  the  ground  a 
little  below  the  surface,  and  that  of  the  snow  that 
covers  it ;  (2)  the  vast  quantities  of  snow  that  fall 
on  the  great  mountain  ranges,  as  the  Himalayas, 
the  Alps,  and  the  Rocky  Mountains,  serve  as  per- 
petual feeders  of  the  rivers. 

The  quantity  of  snow  that  falls  on  an  extensive  range  of 
mountains,  such  as  the  Alps,  is  very  great.  Agassiz  ob. 
served  a  fall  of  fifty-seven  feet  in  six  months  at  the  Hospice 
of  Grimsel,  and  observations  during  twelve  years  near  the 
Pass  of  the  Great  St.  Bernard  showed  an  annual  snow-fall 
varying  from  twelve  to  forty-four  feet.  It  has  been  esti- 
mated that  the  average  annual  snow-fall  on  the  Alps 
amounts  to  sixty  feet,  which  is  equivalent  to  six  feet  of 
water. 

Avalanches. — A  large  part  of  the  snow, 
as  already  stated,  gradually  melts  and  flows 
through  the  river-courses  to  the  sea.  Other, 
although  much  smaller  portions,  descend  the 
mountain  slopes  into  the  valleys  as  avalanches. 
The  snow  is  loosened  from  its  bed  by  the  warmth 
of  the  advancing  season,  and  jjlunges  down  the 
steep  declivities  with  frightful  velocity.  Some 
times  the  very  echo  of  a  loud  word  is  enough 
to  disturb  the  overhanging  mass  and  liurl  it 
into  the  valley  below. 

Many  Instances  are  on  record  of  the  appalling  destruc- 
tion wrought  by  this  scourge  of  the  Alps,  whole  villages 
having  been  overwhelmed,  and  hundreds  of  lives  destroyed 
by  a  single  avalanche.  Thick  forests  are  the  best  protection 
against  danger  from  this  source,  and  in  former  times  the 
penalty  of  death  has  been  adjudged  against  any  who  should 
destroy  a  single  tree  of  the  protecting  barrier. 

'3.  Glaciers  (from  the  French  ^/ace,  ice,)  are 
vast  masses  of  ice  filling  mountain  valleys.  Im- 
agine a  river  descending  a  ravine  to  be  dammed 
up  so  as  to  fill  the  ravine  completely,  and  then  to 
be  frozen  solid.  This  "-ill  give  you  some  concep- 
tion of  a  glacier. 

Formation. — The  process  by  which  glaciers 
are  formed  aj^pears  to  be  as  follows  :  the  snow 
tliat  falls  in  elevated  ravines  gi-adually  becomes 
compacted  in  structure,  owing  to  its  partial  melt- 
ing by  the  sun's  rays,  and  from  the  pressure  of  its 
own  weight. 

If  we  should  follow  one  of  these  ravines  down- 
ward, we  should  find  the  snow  growing  more  and 
more  solid  under  our  feet,  until  we  reached  the 
snow  line.  Below  this  line  we  should  find  the 
compacted  snow  turned  to  ice.  Following  tlie 
course  of  the  ravine  we  should  observe  that  the 
ice  mass  filled  it  from  side  to  side  and  terminated 


HAIL,  SNOW,  AND    GLACIERS. 


95 


at  length  among  the  gardens  and  pastures  of  the 
lower  valleys,  a  stream  of  water  gushing  forth 
from  its  cavernous  extremitj-.  TJiis  is  a  (jlacler  of 
the  first  rank.  Others  again,  smaller  in  extent, 
and  containing  comj^aratively  little  ice,  never 
reach  tlie  lower  valleys.  Tiiese  are  glaciers  of  the 
second  rank. 


THE  MER-DE-GLACE.— (Prom  a  Iliotograph.) 

The  compacted  snow  reaches  about  to  the  snow- 
line, and  is  called  the  neve  (na-va).  The  neve  is 
in  general  about  luilf  the  density  of  ice,  or  more 
than  three  times  that  of  snow. 

Motion  of  the  Glaciers. — Solid  and  immov- 
able as  these  mighty  seas  of  ice  appear,  tliey  are 
really  in  motion.  Long  before  glacier  motion 
was  suspected  by  scientific  men,  it  liad  been  known 
to  the  mountaineers  that  blocks  of  stone  lying 
upon  the  surface  of  glaciers  moved  slowly  down- 
ward. 

A  large  number  of  carefully  conducted  observa- 
tions have  been  made,  which  prove  not  only  that 
the  glacier  has  motion,  but  that  its  motion  closely 
resembles  that  of  a  river.  It  is  swiftest  in  the 
centre,  and  slower,  owing  to  the  friction,  near  the 
sides  and  bottom.  Notwithstanding  this  move- 
ment, the  termination  of  the  glacier  retains  about 
the  same  position  from  year  to  year,  because  it  is 
melted  away  as  fast  as  it  moves  downward. 

Rate  of  Motion. — The  rapidity  of  the  motion  of 
a  glacier  depends  upon  the  sfeason  of  the  year,  the 
size  of  the  glacier,  and  the  inclination  of  its  bed. 
The  motion  is  more  rapid  in  summer  than  in  win- 
ter, in  the  day  time  than  at  night,  and  in  a  large 
and  deep  glacier  than  in  a  small  one. 

Tlie  average  rate  j'er  year,  for  glaciers  of  the 


first  rank  in  the  Alps,  is  not  far  from  100  yards  ; 
for  glaciers  of  the  second  rank,  not  more  than 
one  quarter  of  the  same  amount. 

The  middle  of  tlie  Mer-de-Glace  was  found  by 
Tyndall  to  move  thirty  inches  a  day  in  summer, 
and  half  as  much  in  winter. 

The  following  figures  express  in  yards  the  motion,  during 
one  year,  of  a  row  of  poles  set  in  a  straight  line  across  the 
glacier  of  the  Aar,  by  Prof.  Agassiz: 
5.  20.  48.    55.  02.  G4.    07.  09.  70.  68.  04.    54.  47.  30.  21. 
n.  1. 

The  central  part,  it  will  be  observed,  moved  about  eighty 
yards  a  year. 

Some  glaciers,  notably  that  of  the  Rhone,  tell 
their  own  tale  of  their  movement  down  the  valley. 
On  their  surface  concentric  curves  may  be  ob- 
served bulging  toward  the  lower  end  of  the  glacier. 
These  show,  as  clearly  as  a  line  of  stakes,  the  more 
rajjid  movement  of  tlie  central  portion  of  the 
glacier. 

Owing  to  the  slowness  of  the  glacier  motion, 
what  is  now  the  upper  end  of  the  glacier  may  be 
a  century  or  more  before  it  gets  to  the  foot  of  the 
mountain. 

Theory  of  Glacier  Motion. — Various  tlieo- 
ries,  none  of  which  is  in  all  respects  satisfac- 
tory, have  been  advanced  to  account  for  glacier 
motion  and  the  accompanying  phenomena.  The 
first  thing  to  be  accounted  for  is  the  motion  itself. 
Two  causes  for  this  maybe  given  :  (1)  gravitation  ; 
(2)  expansion  within  the  glacier.  It  is  probable 
that  both  these  take  part  in  producing  the  motion. 

Gravitation,  or  the  weight  of  the  glacier,  would 
naturally  draw  the  mass  down  the  slopes  of  the 
valley. 

Expansion  within  the  glacier  needs  explanation. 
When  the  water  from  the  melted  surface  of  the 
glacier  percolates  downward  into  the  interior  of 
the  mass,  it  encounters  a  temperatitre  of  32°  Fahr. 
It  freezes  and  of  course  expands.  Its  expansion 
must  necessarily  take  place  in  the  direction  of 
least  resistance,  i.e.,  tow-ard  the  lower  end  of  the 
valley.  When  we  recollect  that  freezing  water 
will  burst  a  plugged  bombshell  [see  p.  43],  we  can 
i-eadily  see  that  a  force  will  be  developed  by  the 
water  freezing  in  the  glacier-mass  quite  sufficient 
to  aid  materially  in  tirging  forward  its  enormous 
weight. 

Regelation. — The  facts  must  now  be  considered, 
first,  that  the  ice  of  a  glacier  accommodates  itself 
to  the  shape  of  its  enclosing  valley  very  mtich  as 
a  river  does  to  its  channel ;  and,  second,  that  after 
fracture  its  parts  reunite.  These  phenomena  are 
explained  by  what  is  known  as  regelation  or  second 
freezing.  If  we  pound  a  mass  of  ice  into  fi'ag- 
ments  and  then  moisten  the  broken  surfaces,  the 


9fi 


HAIL,  SNOW,  AND    G^CIERS. 


k 


fragments  will  readily  freeze  compactly  together 
again. 

This  is  what  occurs  in  a  glacier.  In  passing 
throiisrh  narrow  gorges  it  is  crushed  and  broken, 
and  in  gliding  over  steep  irregularities  in  its  bed  it 
is  cracked  and  splintered.  The  lower  parts  break 
away  from  the  upper,  and  fissures  of  great  depth 
called  crevasses  are  formed,  as  shown  in  the  fol- 
lowing illustration. 

But  after  the  ice  has  been  thus  bi-oken  and 
splintered  or  sundered  by  crevasses,  it  reunites  and 
forms  one  compact  mass.  The  crevasses  admit 
warm  air,  and  their  walls  are  perhaps  slightly 
thawed,  or,  the  ice  on  the  top  of  the  glacier  being 
melted,  water  trickles  down  and  moistens  the 
fractured  surfaces.  In  this  condition  the  mass  of 
fragments  is  compressed  by  its  confining  valley- 
walls,  tlie  sundered  portions  are  brought  together 
again,  and  regelation  occurs. 

Effect  of  pressure  on  melting  point  of  ice. — It  appeare  from 
recent  experiments  that  under  jiressure  ice  melts  at  a  lower 
temperature  than  32  Fahr.  If  a  wire  weiglited  at  each  end 
be  caused  to  cut  tlirough  a  block  of  ice,  water  will  be  seen 
flowing  round  the  wire,  while,  in  the  cut  behind  or  above 
the  wire,  it  is  found  to  be  frozen.  This  experiment  has  an 
important  bearing  upon  the  phenomena  of  glacier  motion. 
Pressure  is  obWously  exerted  by  certain  portions  of  the 
glacier  upon  others,  especially  when  the  glacier  is  squeezed 
within  gorges.  If  this  pressure  develop  heat  enough  to 
bring  the  melting  point  of  ice  to  28'  instead  of  32°,  it  is 
easy  to  see  how  the  onward  movement  of  the  glacier  would 
be  facilitated  by  reason  of  its  partial  liquefaction. 

MoRAiXES.  —  The  rocks  and  dchns  brought 
down  from  the  slopes  of  the  ravine  by  the  action 
of  the  frost  and  by  avalanches,  accumulate  along 
the  sides  of  the  glacier.  Hence  a  dark  band  of 
earth  and  stones  may  be  seen  upon  each  side,  va- 
rying according  to  the  character  of  the  rock  en- 
countered. These  bands  are  called  moraines. 
Occurring  at  the  sides  they  are  called  lateral  mo- 
raines. 

At  the  confluence  of  two  glaciers,  the  moraines 


which  skirt  the  two  sides  that  join  are  united, 
and  form  a  medial  moraine.  If  another  glacier 
unites  with  this  again,  a  second  medial  moraine  is 
formed  in  the  same  manner. 


Note. — In  the  accompanying  cut  It  will  be  seen  that  the 
Glacier  du  Gi'aiit  unites  first  with  the  Glacier  des  I'erladee,  and 
from  their  jiiii'-tiou  the  dotted  line  shows  the  medial  moraine 
formed  from  the  right  moraine  of  the  G^ant  glacier  and  the 
left  moraine  of  the  Pi5riades.  Where  the  glacier  thus  rein- 
forced receives  the  Glacier  cie  I.i'chaud,  another  medial  moraine 
is  formed  ;  and  a  third  where  the  Talefre  adds  its  tributary 
stream.    By  the  juuctiou  of  tbesu  is  formed  the  Uer-de-61acc. 


1    s. 


MORAINES  (a,  b,  c,  d.  e)  of  the  mer-de-glace. 

The  earth,  stone  and  boulders  brought  down  on 
the  glaciers  form,  at  the  lower  end  of  the  glacier, 
where  the  ice  melts  and  leaves  them,  immense  de- 
posits, called  terminal  moraines. 

Transporting  Power  of  Glaciers. — The  ex- 
istence of  what  are  known  as  "  boulders "  and 
*  "rocking  stones,"  or  "erratics,"  as  they  are 
also  called,  is  exjilained  by  the  transporting  power 
of  glaciers.  Such  stones  have  been  portions  of 
ancient  moraines.  And  therefore,  from  the  pres- 
ence of  boulders,  we  argue  that  in  former  ages 
glaciers  moved  over  certain  regions  where  they 
are  now  unknown.  A  belt  of  country  extend- 
ing from  the  Baltic  to  the  Black  Sea  has  been 
strewn,  by  glaciers  and  drift-ice  of  a  former  period. 


^  "  Rocking  stones  "  are  large  blocks  of  stone  which  are  so  balanced 
that  they  may  be  rocked  by  a  posh.  They  are  called  "  erratics,"  i.  e.. 
wanderers,  because  found  at  a  distance  from  their  original  site. 


HAIL,  SNOW,  AND    GLACIERS. 


97 


with  boulders  that  were  rent  from  the  Scandina- 
vian Mountains. 

A  similar  process  is  still  going  on  in  the  trans- 
portation of  l)oulders  southwardly  from  the  Arctic 
olifEs.  They  are  borne  by  the  glaciers  of  Green- 
land to  the  shores  of  Baffin  Bay,  and  thence  to  the 


ICE    AND    BOULDERS. 


Banks  of  Newfoundland,  where,  meeting  with  the 
Gulf  Stream,  they  are  dropped  by  the  ice,  and  de- 
posited on  the  bottom.  Thus  these  banks  are 
formed. 

Glaciers  as  River  Sources. — The  glacier,  as 
it  imperceptibly  glides  down  the  mountain,  is 
melting  all  the  time,  and  the  traveller  upon  its 
rugged  surface  may  hear,  far  down  in  its  creviced 
depths,  the  sound  of  running  water,  which  gathers 
volume  from  a  thousand  trickling  streamlets,  and 
at  last  issues  forth,  the  never-failing  source  of 
some  noble  river. 

The  Rhine,  the  Rhone,  and  many  tributaries  of 
tlie  Danube  and  Po,  spring  from  glaciers  in  the 
region  around  the  St.  Gothard  ;  and  every  one  of 
the  hundreds  of  glaciers  found  among  the  Alps 
nourishes  some  stream,  that  it  may  fertilize  the 
land  and  cheer  the  heart  of  the  husbandman.  The 
Ganges,  in  India,  leaps  out  from  under  a  glacier,  a 
torrent  forty  yards  in  width. 

Distribution  and  Size  of  Glaciers. — Gla- 
ciers of  enormous  size  are  found  in  the  Arctic  re- 
gions. Probably  most  of  the  valleys  in  Greenland 
and  Spitzbergen   are   occupied    by  them. 

The  grandest  glacier  region  of  the  temperate  zone 
is  that  of  the  Himalayas.  The  glacier  of  Bepho, 
in  one  of  the  valleys  of  the  Karakorum  range,  is 
38  miles  in  length — about  four  times  as  long  as  the 
Mer-dc-Glace — and  covers  hundreds  of  square  miles 
in  area.  Many  others  in  the  same  region  are  of 
nearly  equal  extent. 


It  is  estimated  that  the  total  number  of  glaciers 
in  the  Alps  is  about  .500,  and  that  the  surface  con- 
stantly covered  by  snow,  nive,  and  ice  is  more  than 
1,000  square  miles.  The  tliickness  of  the  Alpine 
glaciers  is  believed  to  vary  from  200  feet  to  2,000. 
The  PjTenees  and  the  Scandinavian  mountains 
contain  glaciers  of  the  second  rank.  Large  ones 
exist  in  the  Caucasus. 

In  the  New  World,  Greenland  and  Alaska  have 
glaciers  far  surpassing  in  magnitude  those  of  the 
Old  World.  The  Humboldt  Glacier,  in  Green- 
land, is  more  than  sixty  miles  in  breadth,  tliree 
hundred  feet  deep,  and  of  unknown  length. 
Glaciers  of  large  size  are  found  u]>on  Mt.  Shasta, 
and  upon  Mts.  Rainier  and  Tacoma.  The  Andes, 
except  in  Patagonia,  are  destitute  of  them. 

4.  Icebergs. — The  glaciers  of  tiie  ])olar  re- 
gions are  not  melted  into  rivers  like  those  of  tern- 
perate  latitudes.  Their  lower  extremity,  there- 
fore, is  pushed  out  into  the  sea,  and  mountain-like 
masses  are  broken  off  from  time  to  time  and  borne 
away  by  ocean  cuiTcnts.    These  are  called  icebergs. 

Distribution. — On  the  polar  side  of  55°  south,  the  sea,  all 
the  way  round  the  earth,  is  studded  more  or  less  thickly 
with  icebergs,     [See  Isothermal  Chart,  pp.  72,  73.] 

During  his  Antarctic  voyage  in  1841,  Sir  James  Ross 
sailed  450  miles  along  an  unbroken  barrier  of  ice.  It  stood 
180  feet  out  of  the  water,  and  was  aground  in  water  1,500 
feet  deep. 

Admiral  D'Urvillc  fell  in  with  one  off  the  Cape  of  Good 
Hope  13  miles  long  and  100  feet  high.  I  have  met  with 
them  myself  as  near  the  equator  as  37'  south  latitude.  In- 
deed, icebergs  enough  come  from  the  unexplored  Antarctic 
regions  to  stud  an  area  as  large  as  the  continent  of  Asia ; 
for  navigation  is  endangered  there  by  ice  throughout  an 
area  of  not  less  than  15,000,000  square  miles. 

On  the  north  side  of  the  equator  icebergs  are  found  only 
in  the  Atlantic;  never  in  the  Pacific  Ocean.  They  drift 
out  from  their  nurseries  in  the  polar  regions  with  the  cold 
currents  whicli  bear  them  southwardly  until  they  disajipear 
in  the  warm  waters  of  the  Gulf  Stream.  They  frequently 
lodge  on  the  Banks  of  Newfoundland,  where  they  greatly 
imperil  navigation. 

TOPICAL  ANALYSIS. 

\^.    HAIL,    SNOW,    AND   GLACIERS. 

1.  Hail. 

Size  of  hailstones.    Formation. 

Limits  of  pnow  fall.  Of  perpetual  snow.  Offices  of 
snow.  Amount  of  snow-fall  in  mountain  regions. 
Avalanches.    Cause,    Destructive  effects, 

3.  Glaciers. 

Fonnation.  Glaciers  of  the  first  rank.  Second 
rank.  Xh'e.  Motion.  Resemblance  to  that  of  a 
river.  Circumstances  affecting  rapidity  of  mo- 
tion. Rate  of  motion.  How  determined.  Indi- 
cations of  motion  on  the  surface.  Theory  of 
motion.     Causes  of  motion.    Regelatlon,     Ore* 


2.  Snow. 


98 


ELECTRICAL    AND    OPTICAL   PHENOMENA. 


vassee.  Moraines.  Origin.  Lateral,  medial  and 
terminal  morainoH.  Transporting  power  of  gla- 
cier.-. Former  glacier  regions.  <;lacier:i  as  river 
eonrcee.  Distribution  and  «ize  of  glaciers, 
Himalayan  region.     Tlu;  New  World. 

4.  Icebergs. 

Origin  and  ciinractcr.    Distribution. 

Test  Questions.— How  can  eo  cold  a  t^ubstance  as  pnow  be  a  pro- 
tector from  cold  ?  Why  should  the  enow-fall  be  eo  much  greater  on 
mountains  than  elsewhere  ?  Do  you  know  of  any  other  j)lienomenon 
similar  to  avalanches  In  character  and  destructive  effects  ?  At  the  rate 
of  100  yard8  per  year,  how  long  would  it  take  ice  to  move  from  the 
upper  to  the  lower  end  of  a  valley  six  miles  long  ?  If  there  are  four 
moraines  on  a  glacier,  how  many  smaller  glaciers  have  united  to  form 
it  ?  Icebergs  project  about  1-9  out  of  the  water  ;  how  deep  will  one  ex- 
tend which  projects  100  feet,  the  size  being  the  same  above  and  below 
the  water  ? 


VII.     ELECTRICAL   AND    OPTICAL    PHE- 
NOMENA. 

1.  Atmospheric  Electricity. — The  at- 
mosphere is  almost  invariably  in  a  jjositively 
electrified  condition  ;  the  surface  of  the  earth,  in 
relation  to  the  air,  appears  to  be  always  negative. 
In  other  words,  the  air  seems  always  to  contain 
more  electricity  than  the  earth.  At  the  same 
time,  it  is  to  be  remembered  tliat  the  conducting 
power  of  the  earth  may  render  very  difficult  the 
detection  of  its  true  electrical  condition. 

The  electricity  of  the  atmosphere  manifests 
itself  chiefly  in  lightning  and  auroras. 

Lightning  is  of  three  kinds — zig-zag,  sheet- 
lightning  and  ball-lightning. 

Zig-zag  lightning  consists  of  flashes  passing 
between  two  bodies  of  air  or  clouds,  or  between  a 
cloud  and  the  earth,  which  are  in  opposite  electri- 
cal conditions.  The  electricity  takes  the  path  of 
least  resistance,  and  since  different  portions  of  the 
air  have  diilerent  conducting  powers,  the  jiathway 
of  the  lightning  naturally  becomes  zig-zag. 
Sometimes  the  flash  divides  and  jiresents  a  forked 
appearance. 

Shfet-lightning,  frequently  called  heat-lightning, 
appears  as  a  glow  of  light  illuminating  vast  clouds 
and  even  large  areas  of  the  sky.  It  is  probable 
that  this  kind  of  lightning  is  the  reflection  of  the 
liglitning  of  some  distant  storm. 

Ball-lightning  appears  in  the  shape  of  globular 
masses  of  fire,  which  explode  with  violence.  It  is 
of  rare  occurrence. 

Thmider  is  considered  to  be  occasioned  by  the  sudden 
rushing  together  of  the  portions  of  the  atmosphere  that  have 
been  divided  by  a  flash  of  lightning.  It  is  not  heard  at  a 
greater  distance  than  fourteen  miles. 

The  flash  is  seen  instantaneously.  The  sound  requires 
about  five  seconds  to  travel  one  mile.  Hence,  if  after  see- 
ing the  lightning,  we  count  the  number  of  seconds,  or  pulse 
beats,  until  we  hear  the  thiuider,  it  is  easy  to  ascertain  how 
near  the  flash  has  been  to  us. 


Thundeu-storms  are  usually  very  local,  but  this 
is  not  always  the  case.  That  which  accompanied 
the  "bursting"  of  the  May  monsoon  in  1848  ex- 
tended over  an  area  of  GOO  miles  in  length  and 
fifty  m  breadth. 

In  general  the  electricity  does  not  pass  from  the 
air  to  the  eartli,  but  only  from  one  ijortion  of  the 
atmosphere  to  another.  When  a  discharge  to  the 
earth  does  occur,  the  efiEects  are  often  very  destruc- 
tive. The  strongest  trees,  if  struck,  are  rent  and 
stripped  of  their  branches,  the  sap  being  suddenly 
converted  into  steam,  and  an  explosion  actually 
taking  place.  Animals  and  men  who  are  struck 
are  almost  always  killed. 

I     DistribuHon. — Thunder-storms  are  much  more  frequent 
in  warm  than  in  tool  climates.     They  occur  in  that  section 
I  of  the  torrid  zone  known  as  the  belt  of  Constant  Precipita- 
I  tion  almost  every  day  in  the  year. 

jV  The  Auroka  Borealis,  or  Northern  Lights, 
is  a  luminous  a2ipearance  often  observed,  as  the 
name  implies,  in  the  northern  heavens.  In  the 
southern  hemispehre  the  same  phenomenon  is 
called  Aurora  Anstralis. 


AURORA   IN   ARCTIC   REGIONS. 


The  form  of  the  aurora  varies  greatly.  Some- 
times it  is  simply  an  arch  of  light  spanning  the 
sky  near  the  horizon,  with  quivering  streamers  of 
white,  green,  or  crimson  light,  shooting  fitfully  to 
the  zenith.  Sometimes  mere  masses  of  colored 
light  are  observed.  At  times  the  whole  heavens 
are  flushed. 


ELECTRICAL   AND    OPTICAL    PHENOMENA. 


99 


Nature. — The  aurora  is  simply    an  electrical 


phenomenon.     Tlie 
probability  of  this. 


following  facts  establish  the 


(1)  The  delicule  shades  of  rose,  and  purple,  and  violet, 
wliieh  cliaractcrize  the  more  brilliant  aiii'oras,  can  be  pro- 
duped  by  passing  the  spark  from  an  electrical  machine 
tlirough  a  partial  vacuum,  as  has  been  remarkably  illustrated 
by  some  experiments  of  Mr.  Crookes,  of  England. 

It  has  been  computed  from  observations  of  a  large  num- 
ber of  auroras,  that  the  beams  never  approach  nearer  to  the 
earth's  surface  than  forty-five  miles,  and  sometimes  extend 
from  it  to  the  distance  of  more  than  500.  Hence  the  at- 
mosphere in  which  the  auroral  light  is  displayed  is  very 
attenuated,  like  that  through  which  the  electricity  is  passed 
in  the  experiments  alluded  to. 

(2)  Positive  evidence  of  the  electric  origin  of  the  aurora 
is  found  in  the  effect  produced  upon  the  telegraph  wires 
during  an  auroral  display.  The  aurora  sometimes  has  actu- 
ally rendered  unnecessary  the  use  of  a  battery  in  telegraph- 
ing. The  effect  is  similar  to  that  occasioned  during  a 
thunder-storm,  but  usually  of  less  intensity. 


(3)  The  magnetic  needle,  also,  is  disturbed  during  auroras 
in  a  degree  corresponding  to  the  brilliancy  of  the  display. 
During  the  splendid  aurora  of  September  2d,  185!).  the  dec- 
lination of  the  needle,  at  Toronto,  changed  nearly  4°  in 
half  an  hour.  Tliis  aurora  extended  romid  the  globe,  for  it 
was  seen  in  Europe  and  North  America,  and  in  the  Sand- 
wich Islands,  and  it  indicated  its  presence  in  Northern  Asia, 
where  the  sky  was  cloudy,  by  magnetic  disturbances. 

Distribution. — Auroras  are  more  frequent  as  we 
approach  the  poles.  Witliin  tlie  tropics  they  are 
almost  unknown.  Thus  their  law  of  distribution 
is  just  the  reverse  of  that  whicli  governs  tlie  dis- 
tril)ution  of  lightning. 

In  North  America  the  zone  of  greatest  frequency 
lies  between  50°  and  63°  north  latitude.  Here 
the  displays  are  of  almost  daily  occurrence.  North 
and  south  of  this  belt  the  annual  number  rapidly 
decreases,  being  on  the  ayerage  about  ten  in  lati- 
tude 40°,  and  the  same  in  latitude  78°.  In  Europe 
the  zone  of  greatest  frequency  lies  between  06° 
and  75°  north  latitude. 

St.  Elmo's  Fire.— In  storms  at  sea  the  masts 


and  yards  of  the  ship  are  sometimes  tipped  with 
balls  of  electric  light.  The  superstitious  sailor 
trembles  witli  awe  at  the  sight  of  ihciii,  believing 
tliem  to  be  the  souls  of  the  dead. 

They  are  due  to  electricity  passing  witliout  noise, 
when  the  clouds  are  low,  between  tlie  clouds  and 
the  tijJS  of  the  spars  of  the  ship. 

2.  Optical  I'henomcnd. — Tlie  most  im- 
portant of  all  the  optical  phenomena  connected 
with  the  atmosishere  is  also  the  most  common. 
It  is  the  diffusion  of  light.  This  is  brought  about 
by  reflection  and  refraction.  By  the  former,  light 
is  j^ropagated  from  particle  to  particle  of  the  at- 
mosphere. By  the  latter,  it  is  retained  above  the 
horizon  when  the  sun  has  actually  gone  down,  and 
it  is  bent  into  the  atmosphere  before  he  has  actually 
risen  above  the  horizon. 

Eefraction  and  reflection  give  rise  to  the  ex- 
quisite variety  of  colors  which  deck  the  morning 
and  evening  sky.  Tliey  also  occasion  tlie  less  fre- 
quent phenomena  of  rainbows,  halos  and  mirage. 

The  Rarnhow  is  an  arch  of  colored  light  wliich  spans  tlie 
heavens  during  a  storm.  It  is  seen  only  wlien  the  sun  is 
shining  at  the  same  time  that  rain  is  falling.  The  descending 
drops  separate  the  white  sunlight  into  its  elementary  colors. 

Halos  are  rings  of  prismatic  colors  round  the  sun  or  moon. 
They  are  really  circular  rainbows,  and  are  probably  due  to 
the  refracting  power  of  the  small  ice-ci-j-stals  composing 
cirrus- clouds. 

Mirage.  Another  effect  of  refraction  and  reflection  is 
commonly  called  mirage.  It  is  often  obsen'ed  in  the  desert. 
Distant  villages  seem  under  its  influence  to  be  near  to  the 
spectator,  or  to  be  suspended  in  the  heavens  above.  Some- 
times the  traveller  thinks  he  is  approaching  a  pool  of  spark- 
ling water,  and  hastens  to  quencli  his  thirst,  when  he  finds 
that  he  has  been  pursuing  a  mirage. 

Mirage  is  also  observed  at  sea,  distant  ships  being  seen  ele- 
vated above  their  true  position,  or  even  inverted  in  tlie  air. 


TOPICAL  ANALYSIS. 
VH.    ELECTRICAL   AND   OPTICAl    PHENOMENA. 


^ 


1.  Atmospheric  Electricity. 

Electrical  condition  of  air  and  enrth  compared. 
Character.     How  mjinifcsted. 

Kinds  of  lightning.  Zig-ua^  lii^htning.  OiiifJe  of 
its  broken  and  forked  conrse.  Sheet-lightning. 
Ball-lightning.  Cause  of  thunder.  At  what  distance 
audible.    Distance  of  the  flash.    Flow  computed. 

Area  and  distribution  of  Ihunder-slorms.  Destruc- 
tive eflfects  of  lightning. 

Aurora  Borealis  and  Australia.  Form  and  appear 
ance.  Nature.  Reasons  for  considering  it  an  elec- 
trical phenomenon.  Distribution.    St.  Elmo's  fire. 

2.  Optical  Phenomena. 

Diffusion  of  light.  How  caused.  Other  effects. 
Description  of  the  rainbow,  halos  and  mirage. 

Test  Questions.— If  the  thunder  is  heard  in  three  seconds  after  the 
flash,  what  is  the  distance  of  the  discharge  ?  Why  does  the  rainbow 
show  seven  colors  ? 


TOPICAL    ANALYSIS    FOR    REVIEW. 


Physical  Properties  of  the  Atmosphere. 


The  Atmosphere.     .       Composition.    Ueea  of  inj^edients. 
(  Evidences  that  the  air  has  weight. 
Amount  of  pressure.    Effect  on  the  bolline  point. 

The  weight  of  the  air.  -j  Causes  of  variation  in  pressure.  \  SS*^^'!  ^l  ^-l'"»e<-''^  of  't^^el. 

"  '  ^  i  Effect  of  changes  in  weight  of  air. 

Height  of  the  atmoKi>herc. 
Change  of  density  with  height. 


Climate.    •     • 


Climate )  Main  Elements. 

j  Modifying  Causes. 
Distance  from  the  equator.  J  Effect  on  annual  temperature. 

I  Climatic  contraj^ts. 
Distance  from  the  sea.      .   j  Insular  climates.    Causes  which  moderate  them. 

/  Inland  climates.    Reasons  for  their  extremes. 
Prevailinjj  wind^*  and  ocean  currents. 

Height  above  the  sea-level.     Reasons  for  effect  of  elevation.    General  rule. 
Isothermal  lini;8.      .     .       j  Rt;lation  to  pumllels. 

j  Zones  or  temperature. 


Winds  and  Circulation  of  the  Air. 


f  Causes  of  winds.    . 
General  Circulation. 


Trade  winds. 


Variable  Winds, 


Heat.    Moisture. 

(  Location  of  constant  ascending  currents. 

<  Causes  which  complicaie  circulation. 

(  Classification  of  winds. 

J  General  character.    Direction. 

/  Cause  of  westward  trend. 

i  Locality. 

■i  Counter  trades.    Origin.    Proofs.    Direction. 

/  Polar  winds. 


The  calm  belts. 


Periodical  wind: 


ortice  of  winds. 


Equatorial.    Calms  of  Cancer.    Capricorn. 
f  Land  and  sea  breezes.    Benefits  of. 
J  Monsoons.    Cause.    Effect.     Minor  monsoons. 


Oth(-*r  periodic  winds 


)  Desert  winds, 
'  i  Mountain  winds. 


Storms. 


General  Description.    Cyclones.       Classes. 

Cause  of  storms.    Cause  of  sjiiral  movement. 

(  Dinction  of  the  whirl. 
Laws  of  storms J   Forward  motion  of  the  storm. 

I  Calm  at  the  centre.    Causes  of  low  barometer  at  the  centre. 

[  Irregularity  of  land  storms. 
Value  of  storm  laws.    Areas  of  storms. 

I  Difference  between  these  and  hurricanes  and  typhoons. 
Whirlwmds  and  Tornadoes.     .      .}  Destructive  effects. 

(  Dust  whirlwinds.    Waterspouts. 
Distribution. 
Weather  forecasts.     Great  storms  in  the  United  States. 


Moisture  of  the  Air. 


Evaporation  J  Conditions  under  which  it  takes  place. 

'  causes  which  increase  it.  ]  S?>7etf-^W';"""'^^ 
Condensation  and  Precipitation,    j  f,"^^^^  of  water  derived  from  vapor. 
\  Cause  of  precipitation.    Dew-point. 

Formation  of  dew 3  ^^'^^^  "^  clouds. 

j  Difference  m  quantity  on  various  substances. 

Fog How  formed.    Illustrations. 

If  Cirrus.    Cumulus.    Stratus. 
Various  forms. -J  Cirro-cumulus.  Cirro-stratus.  Comulo-stratua 
i  Cumulo-cirro-stratus. 
Velocitv  of  cloud  movement. 
Height.'    OfHces. 

Cause  of  rainfall.    Distribution. 


Rain. 


Regulators  of  rainfall, 


1  Mountains. 
■^  Deserts. 


Various  examples. 

Examples. 

f  Winds.     Dry  aud  wet  winds, 
r  Constant.    Locality-    Cause. 
I   Periodical    i  l'0^'^''^y-    Kainy  «"<!  dry  f'easons  in 


Classification.  \   Periodical    ]  New  aud  Old  WorUi.^ 

[  Variable.     Where  found. 
Excessive  and  deficient  rainfall.  ]  gfficiety"''=cLaes. 


Hail,  Snow  and  Olaciers. 


Hail. 


Glaciers. 


Icebergs. 


Size.    Formation. 

Limits  of  gnow-fall.    Of  perpetual  snow. 

Otliccs.    Amount  of  snow-fall  in  mountain  regions. 

Avalanches.  ]  g"fr^etive  effects. 

Formation.    Glaciers  of  the  first  rank.    Second  rank. 

I  Circumstances  afl^ecting  rapidity  of  motion.    Average  rate. 

-?  ™,  - ,,   --         1  Causes. 


Motion. 


j  Theory  of  Motion.. I  j^^^g,^^o„      Crevasses.     Effect  of  pressure. 


Moraines.    Origin.    Kinds. 
Transporting  Power. 


(  Origin  of  boulders. 

)  Former  glacier  regions. 
I  Glaciers  as  river  sources. 
[  Distril)Ution  and  size. 

Origin.    Distribution. 


Electrical  and  Optical  Phenomena. 


Atmospheric  Electricity. 


Aurora  Borealis  and  Australis. 

St.  Elmo's  Fire. 

Optical  Phenomena.     .     .    . 


Character.    How  manifested. 

Kinds  of  lightning. 

Cause  of  thunder.    Distance  of  the  flash. 

Distribution  of  storms.    Destructive  effects. 

Form  and  appearance. 

Nature.    Distribution. 

Diffusion  of  light.     How  caused. 

nfh*.r  pffpnr«    J  *^°'or  of  clouds.    The  rainbow, 
Utner  etiects.  -j  pyalos.    Mirage. 


PART      V, 


LIFE, 


I.    EELATIONS  BETWEEN    PLANTS  AND 
ANIMALS. 

1.  Life.  —  In  the  foregoiug  pages  we  have 
treated  of  the  land,  the  water,  and  the  air.  These 
are  known  as  the  inorganic  or  lifeless  portions  of 
the  eartli.  We  come  now  to  that  which  is  organic. 
This  term  (derived  from  the  Greek  organon,  an  in- 
strument) signifies  possessed  of  organs  or  instru- 
ments adapted  for  doing  certain  things,  e.g.,  lungs 
for  breathing,  hands  for  handling,  feet  for  walking. 
It  is  therefore  used  as  equivalent  to  living. 

Of  living  things  there  are  two  grand  divisions, 
plants  and  animals  ;  or,  as  they  are  often  compre- 
hensively called.  Flora  and  Fauna. 

In  Physical  Geography  we  have  to  consider  ; 
first,  the  relation  of  each  of  tliese  to  the  other ; 
and  secondly,  their  distribution  and  its  causes. 

2.  3Iutual  Dependence  of  Plants  and 
Animals. — The  relations  between  the  plants 
and  animals  of  the  world  are  such  that  neither 
could  exist  without  the  other.  Each  prepares 
what  the  other  requires. 

Oxygen  Required  by  Animals. — The  various 
forms  of  animal  life  require  a  constant  supply  of 
that  element  of  the  air  known  as  oxygen.  Even 
the  fishes,  though  they  seem  to  breathe  water, 
really  extract  oxygen  from  the  water  by  means  of 
their  gills  ;  for  in  water  a  certain  amount  of  at- 
mospheric air  is  always  present. 

When  taken  into  the  bodies  of  animals,  oxygen 
undergoes  a  change  which  renders  it  not  only  unfit 
for  breathing  again,  but  actually  poisonous.  It 
forms  a  compound  called  carbonic  acid  gas.  This 
gas  is  also  produced  in  the  process  of  fermenting 
beer,  and  if,  as  sometimes  occurs,  a  man  falls  into 
the  vat,  it  is  almost  certain  death  to  him.  In  an 
atmosphere  containing  large  quantities  of  it,  there- 
fore, animal  life  would  not  be  possible. 

Some  arrangement  is  required  to  remove  such  a 
dangerous  ingredient  from  the  atmosphere.  This 
is  accomplished  by  the  various  forms  of  plant  life. 
Let  us  see  how  it  is  done. 

Oxygen  Prepared  by  Plants. — The  leaves  of 


plants  have  upon  their  surface  a  multitude  of  lit- 
tle pores  or  mouthlets.  Tlirough  these  the  leaves, 
while  the  sunshine  rests  upon  them,  have  the  sin- 
gular jjroperty  of  taking  in  carbonic  acid.  In  the 
plant  this  gas  undergoes  a  change.  Its  parts,  car- 
bon and  oxygen,  were  put  together  in  the  body  of 
the  animal :  they  are  put  asunder  in  the  substance 
of  the  plant.  The  charcoal,  which  makes  a  poi- 
sonous compound  with  oxygen,  is  separated  from 
it,  and  employed  by  the  plant  in  building  up  its 
massive  branches,  its  beautiful  flowers,  and  its 
nutritious  fruit. 

While  the  plant  is  thus  appropriating,  or,  as  we  miglit 
say,  digesting  the  carbon  of  the  carbonic  acid,  it  is  also  per- 
mitting the  oxygen  to  escape  back  into  the  atmosphere,  so 
as  to  be  inhaled  once  more  by  the  forms  of  animal  life. 

Food  of  Animals  Supplied  by  Plants. — 
Again,  animals  are  dependent  on  plants  not  alone 
for  what  they  breathe  but  for  what  they  eat.  This 
is  true,  whether  they  are  herbivorous  {grass-eaters) 
or  carnivorous  {flesh-eaters).  For  where  there  is 
no  grass,  or  any  vegetable  production  that  takes  its 
place,  herbivorous  animals  cannot  live  ;  and  where 
they  are  not  found,  carnivorous  animals,  which 
feed  ui^on  them,  cannot  exist. 

On  the  other  hand,  plants  are  indebted  to  ani- 
mals for  the  preparation  of  that  invisible  food 
(carbonic  acid  gas),  upon  which  they  so  largely  de- 
pend, and  from  a  portion  of  which  they  build  up 
their  forms  of  solidity  and  beauty. 

Plants  and  Animals,  Mutual  Checks. ^ — 
Again,  plants  and  animals  may  be  regarded  as 
checks  upon  one  another.  A  certain  proportion  of 
each  is  required  to  keep  uniform  the  composition 
of  the  atmosphere.  If  there  were  too  many  ani- 
mals, there  would  be  too  much  carbonic  acid.  If 
there  were  too  many  plants,  there  would  be  too 
much  oxygen. 

The  i^lants  absorb  the  carbon,  and  throw  off 
oxygen  into  the  atmosphere  ;  the  animals  take  in 
oxygen  and  give  out  carbon.  Thus  the  one  coun- 
teracts the  excessive  action  of  the  other. 

Intervention  of  the  Winds. — But  the  plants 
that  throw  out  oxygen  and  the  animals  that  take 


J02 


RANGE    OF    PLANTS    AND    ANIMALS. 


it  up  again  are  often  far  removed  from  each  other. 
How  is  it  conveyed  from  the  j'lants  wliicli  throw 
it  out  to  the  animals  which  consume  it  ? 

To  effect  the  needed  interchange  and  to  keep 
tlie  air  well  mixed  is  one  of  the  offices  of  that 
wonderful  system  of  winds  of  wliich  you  have 
learned.  They  give  circulation  to  tlie  atmosphere; 
they  bear  off  the  excess  of  gases  from  jjlaces 
where  they  are  not  wanted,  and  deliver  them  for 
use  in  other  parts  of  tlie  world  where  they  are 
needed. 

TOPICAL  ANALYSIS. 
I.    RELATIONS   BETWEEN   PLANTS   AND   ANIMALS. 

1.  Life. 

Organic  and  inorganic  nature.  Flora  and  faniia. 
Points  with  regard  to  them  which  are  considered 
in  physical  geography. 

2.  Mutual  dependence  of  Plants  and  Animals. 

Wliat  animals  require  for  respiration.  Change  of 
this  element  in  the  process.  Effect  of  the 
change.  Dangerous  product  of  respiration,  how 
disposed  of.  Oxygen  prepared  by  plants.  Food 
of  animals  sujiplied  by  plants.  Plants  and 
animals,  mutual  checks.  Inter^'cntion  of  the 
winds. 

Test  Questions.— Wliat  is  the  principal  thing  that  plants  take  up  by 
their  roots?  Aside  from  their  use  in  furnishing  oxygen,  name  some  of 
the  plants  that  are  directly  useful  to  man.  Name  some  that  are  indirect- 
ly useful. 

II.  RANGE  OF  PLANTS  AND  ANIMALS. 

1.  General  Facts. — It  is  a  familiar  fact  that 
the  same  kinds  of  plants  and  animals  are  not 
found  every  wliere. 
Some  forms  are  widely 
distributed,  others  are 
restricted  to  very  nar- 
row limits.  The  region 
within  wliicliany  plant 
or  animal  is  found  is 
Commonly  called  its 
geograph  ical  range. 
The  dandelion  and 
buttercup  blossom 
even  amid  the  glaciers 
of  Greenland.  The 
orange,  the  date,  and 
banana  grow  only 
within  or  near  the 
tropics.    Tlie  gigantic 

water  lily  called  the  Victoria  Eegia  has  been  found 
only  in  the  basins  of  the  Amazon  and  Orinoco. 

The  camel's  thorn  is  peculiar  to  the  desert.  It  is  too  hard 
for  other  animals  to  feed  on,  but  it  supplies  the  camel  with 
food  ou  his  journeys.     Man  converts  it  to  his  use  also.     Its 


roots  strike  deep,  and  it  has  the  faculty  of  collecting  a  sup- 
ply of  moisture  even  amid  tlie  parched  desert.  The  Arab 
makes  an  incision  in  the  plant,  near  the  root,  and  inserts 
a  watermelon  seed  and  covers  it  up.  The  seed  sprouts, 
and  the  vine  becomes  a  jiarasite,  producing  a  melon  of 
delicious  flavor. 

2.   Rainje    Jiependent  on   Climate. — 

Certain  conditions  render  it  possible  or  impossible 
for  the  various  species  of  living  forms  to  exist. 
Of  these  conditions  by  far  the  most  important  are 
temperature  and  moisture. 

Tlie  peculiar  plants  and  animals  of  the  torrid 
zone  would  obviously  die,  if  jilaced  amid  the  cold 
of  the  Arctic  circle  ;  while  it  is  equally  certain 
that  the  polar  bear  and  his  associates  would  be- 
come extinct,  if  they  were  exposed  to  the  scorch- 
ing heat  of  the  tropics. 

Illvstratimis  from  Geology. — The  early  geological  history 
of  the  globe  furnishes  striking  illustrations  of  this  principle. 
The  entire  assemblage  of  animals  that  we  now  find  upon 
the  earth  did  not  simultaneously  spring  into  existence. 
Those  species  first  appeared  which  were  suited  by  existing 
climatic  conditions.  Low  forms  of  animal  life  prevailed  at 
first,  and  then  higher  and  liigher  successively,  until  such 
conditions  arose  as  were  favorable  to  the  life  of  man,  and 
then,  at  length,  his  creation  took  place. 

Many,  moreover,  of  the  animals  that  once  abounded  have 
entirely  disappeared.  Their  existence  is  attested  only  by 
fossil  remains.  Lynxes,  bears,  and  hyenas  once  roamed 
over  the  fields  of  England,  and  crocodiles  swarmed  in  its 
rivers  ;  huge  mastodons,  larger  than  the  modem  elephant, 
flourished  on  what  are  now  the  banks  of  the  Hudson,  and 
browsed  amid  the  forests  of  Siberia.  Their  tusks  are  dug 
up  at  the  mouth  of  the  Lena  and  upon  the  islands  of  New 
Siberia,  in  such  quantities  as  to  form  an  article  of  regular 
commerce,  under  the  name  of  "  fossil  ivory."  The  climatic 
conditions  favorable  to  their  existence  have  ceased,  and 
their  race  has  therefore  become  extinct. 


VICTORIA  KEGIA. 


K 


Modifications  by  Climate. — It  would  follow 
as  a  natural  conclusion  from  the  fact  that  plant 
and  animal  life  are  largely  dependent  on  pjiysical 
conditions,  that  changes  in  these  conditions 
should  bring  about  changes  in  the  plants  and  ani- 


RANGE    OF    PLAN*rS    WnD   ANIMALS. 


103 


THE    THREE    ZONES. 


mals  affected  by  them.  Such  we  find  to  be  the 
fact.  Modifications  of  a  very  extraordinary  nat- 
ure can  be  effected  by  varying  the  "environ- 
ment" of  a  plant  or  animal,  and  allowing  the 
new  environment  to  be  permanent  during  a  suffi- 
cient length  of  time.  Many  of  our  most  valuable 
food  plants  have  been  thus  transformed.  The 
grains  in  general  are  believed  to  have  been  origi- 
nally wild  grasses. 

Our  own  Indian  corn  presents  a  very  interesting 
illustration  of  climatic  modification  in  a  vegetable 
form.  In  the  South  it  often  attains  the  height  of 
12  to  15  feet.  As  we  advance  northward  through 
its  belt  of  cultivation  its  height  diminishes,  until, 
on  tiie  northern  edge  of  the  belt,  it  is  not  usually 
more  than  about  5  feet  high.  -Again,  the  appear- 
ance and  quality  of  its  grain  have  been  singularly 
modified.  It  is  a  familiar  fact  that  we  have  a 
number  of  varieties,  field-corn,  sweet-corn,  pop- 
coi'n,  with  white,  yellow,  brown,  and  even  black 
grains. 

The  common  nasturtium  in  trojiical  countries  is 
a  perennial  tree  ;  farther  north  it  is  dwarfed  and 
becomes  a  shrub  ;  while  in  still  higher  latitudes  it 
is  a  vine  that  lives  no  longer  than  a  single  season. 

Similar  illustrations  might  be  given  of  the  mod- 
ifications of  animal  forms  by  changes  in  their 
physical  conditions.  The  Shetland  pony  and  the 
race-horse  came  from  one  original  stock.  The 
terrier,  the  greyhound,  and  the  mastiff  had  a  com- 
mon parentage. 

3.  Zones  of  Vegetation. — Since  the  extent 


of  the  geographical  range  of  plants  depends  mainly 
on  te^nperainre  and  moisture,  it  follows  that  the 
surface  of  the  earth  may  be  divided  into  zones  of 
vegetation.  These  will  correspond  more  or  less 
closely  with  the  zones  of  temperature.  They  will 
of  course  be  defined  not  by  lines  of  latitude,  but 
by  lines  of  heat,  or  isotherms. 

The  principle  of  division  is  this,  that  within 
belts  or  zones  having  a  certain  average  annual 
temperature,  certain  vegetable  growths  will 
floui'ish  ;  beyond  the  limits  of  such  zones  these 
characteristic  forms  disappear,  and  others  are 
found  which  are  suited  by  the  prevailing  tempera- 
ture. Thus  eacli  zone  has  its  characteristic  forms 
of  vegetable  growth. 

Note. — In  naming  the  zones  of  vegetation  we  borrow  the 
terms  employed  in  the  ordinary  division  by  lines  of  latitude, 
always  remembering,  however,  that  the  signification  of  the 
terms  does  not  remain  exactly  the  same. 

Horizontal  Zones. — The  surface  of  the  earth 
may  be  divided  into  the  following  horizontal  zones 
of  vegetation :  (1)  an  equatorial  zone ;  (2)  two 
temperate  zones  ;  (3)  two  polar  zones. 

TJiC  Equatorial  Zone  extends  north  and  south 
of  the  equator,  and  is  bounded  by  the  annual  iso- 
therms of  70°  Fulir.  It  is  the  zone  of  greatest 
heat  and  most  abundant  moisture,  and  conse- 
quently of  most  luxuriant  vegetation. 

The  characteristic  growth  of  this  belt  is  that  of 
the  palms.  The  trees  do  not  lose  their  leaves  in 
winter. 

T}ie   Temperate  Zones   extend    northward  and 


I'HIN'CIF'AI.  HKlUdNS 
COTTON,  SUGAR-CAME,  CO  FFR,E  MO  TLA^ 


\iioj.  N>"  ^  ■«^w.,H\ 


twj&.Xi^  «\w<T  ^."SrtMBrtJlT- 


io6 


RANGE    OF    PLANTS   AND  ANIMALS. 


Questions  on  the  Chart  of  VEaETABLE  Growths. — 
Into  how  many  zones  of  vegetation  is  the  surface  of  the 
earth  divided  upon  the  chart  ?    Zones,  how  defined  1 

Trace  the  line  of  north  limit  of  trees.  What  vegetable 
products  are  found  north  of  that  line  ? 

Wliich  of  the  cereals  grow  farthest  north  ?  Describe  the 
northern  limit  of  wheat  ;  of  barley,  rye,  and  oats.  What 
grains  might  probably  be  grown  in  Newfoundland  ?  In  Ice- 
hmd  ?  In  difEcrent  parts  of  Norway  and  Sweden  ? 

Trace  the  limits  of  rice.  On  what  jiorfions  of  the  Amer- 
ican continent  is  rice  grown  ?  In  what  parts  of  Europe  and 
Asia  ?  Trace  the  limits  of  palms,  bananas,  and  spices.  Of 
the  vine. 

Wlierp  is  coffee  cultivated  ?  Tea  ?  (Sec  small  map  on 
the  left  of  the  Chart.)  In  what  localities  do  you  find  the 
sugar-cane  ?    Cotton  ? 

What  arc  among  the  products  of  Madagascar  ? 

Where  is  the  mulberry  found  ?  What  use  is  made  of  the 
leaves  of  this  tree  ?  Where  are  the  silk  regions  ?  What 
fruit-trees  do  you  find  in  Japan  ?  In  Australia  ?  In  Norway 
and  Sweden  ?     In  the  West  Indies  and  Bahamas  ? 

At  what  height  above  the  sea  can  potatoes  be  cultivated  ? 
In  latitude  10"  ?  In  latitude  50-  ? 


southward  of  the  equatorial,  and  are  bounded  by 
the  isotlierms  of  32°  Fahr.  Here  the  tro])ical  palms 
disappear,  or  are  replaced  by  dwarfed  representa- 
tives of  the  family. 

The  characteristic  forms  are  those  of  the  decid- 
uous forest  trees — that  is.  those  which  lose  their 
leaves  in  autumn  and  renew  them  again  in  spring. 
The  oak,  the  chestnut,  and  others  which  belong 
to  our  own  forests,  are  familiar  examples  of  these. 

The  colder  parts  of  these  zones  are  marked  by 
the  abundance  of  conifers  (pines,  larches,  spruce 
and  juniper  trees). 

llie  Polar  Zones  extend  north  and  south  from 
the  temperate.  Within  them  the  average  annual 
temperature  is  not  higher  than  32°,  and  in  many 
portions  it  is  below  5°.  Tlie  warmer  parts  of  these 
zones  contain  vast  forests  of  spruce,  pine  and 
larch.  The  colder  portions  are  characterized  by 
the  growth  of  dwarfed  birch,  alder  and  willow 
trees.  But  beyond  certain  limits  trees  wholly  dis- 
appear, and  only  the  lowest  forms  of  plant  life, 
(mosses  and  lichens)  remain. 

Vertical  Zones. — Since,  by  ascending  suffi- 
ciently high,  we  can  pass,  even  in  equatorial  regions, 
through  every  variety  of  climate,  torrid,  temperate 
and  frigid,  it  is  clear  that  there  must  be  vertical 
as  well  as  horizontal  zones  of  vesretation. 

On  the  lower  slopes  of  the  Andes,  for  example, 
we  find  regions  of  palms  and  bananas,  tree-ferns 
and  vines.  These  correspond  to  the  zone  of  equa- 
torial vegetation.  Higher  up  we  encounter  the 
deciduous  trees  of  the  temperate  zone.  Still 
farther  up  we  enter  a  region  closely  resembling 
that  of  the  Arctic  zone  :  the  conifers  are  the  pre- 
vailing type,  while  the  deciduous  trees  are  repre- 


sented by  shrabs  and  dwarfed  specimens.  Near 
the  snow-line  trees  of  every  kind  disappear,  and 
mosses  and  lichens  are  the  only  forms  of  vegeta- 
tion that  can  support  tlie  peiijctual  cold. 


^.'-r-:    \      Reifflon  of  Lichens. 
.VwX'xT^^^'X  RegluQ  of  GrasBes. 

<!    ^-«-   -°  _  —  "^  "x.  ^>^  "^v    Shrubby  Region. 
-        ■!'..«.T.er?.  ^  ■>  --^     ^  -»\ 

i.  1  'l  lV!^^Mti''('|  1?<7/J;]V['.\"'""  "'  '■■Inctona  trees. 

H  f^O  ^  2<^  '» .p  V S^<_  Limit  of  ordinary  large  trees. 

I  >^''''''^'>-''i{'{  .'''//''•''a  Eegion  of  Tree-ferns. 

VERTICAL  ZONES  OP   VEGETATION. 

4.  Bauf/e  of  Food  Plffufs.—li  will  be  of 
interest  to  consider  the  geographical  distribution 
of  those  plants  that  are  of  the  greatest  importance 
to  man.  Of  these,  the  grains  or  cereals,  as  they 
are  called  (barley,  lye,  wheat,  Indian  corn,  rice, 
and  millet),  deserve  attention  first.  Certain  of 
tliem  have,  of  all  plants,  the  widest  geographical 
range,  and  thus  furnish  a  striking  instance  of 
provident  care  in  that  terrestrial  economy  which 
is  as  benign  as  it  is  beautiful. 

Bm-lcy  is  cultivated  in  Europe  as  high  as  70" 
north  latitude,  and  on  the  Asiatic  table-lands  at  an 
elevation  of  13,000  feet. 

Bye  will  grow  in  all  regions  between  07°  north 
and  south  latitude. 

Wheat  has  a  range  almost  equal  to  that  of  rye. 
It  ripens  in  North  America  as  far  north  as  latitude 
55°,  and  in  Europe,  owing  to  the  influence  of  the 
Gulf  Stream,  as  far  north  as  latitude  64°.  In  the 
Himalaya  Mountains  it  is  cultivated  as  high  as 
18,544  feet  above  the  sea,  which  is  a  quarter  of  a 
mile  above  the  Andean  snow-line  of  intertropical 
America.     [See  small  map,  ji.  105.] 

Indian  Corn  will  grow  and  ripen  in  the  open 
air,  from  the  parallel  of  45°  or  50°  north  to  the 
corresponding  parallel  south.  Its  geogi-aphical 
range  embraces  two-thirds  of  the  earth's  surface. 
In  the  torrid  zone  neither  wheat  nor  Indian  com 
do  well  at  the  sea-level,  though  they  produce  finely 
on  the  mountain-sides. 

Millet  is  another  of  the  cereals.  It  is  sparingly 
cultivated  in  the  United  States,  but  it  is  an  im- 
portant article  of  food  in  Egypt,  Arabia,  Turkey, 
and  Italy,  and  is  cultivated  as  far  north  in  Europe 
as  42°. 

Nearly  allied  to  the  cereals  as  an  article  of  diet 
is  the  ^o^«^o.     It  has  a  range  almost  equal  to  that 


RANGE    OF    PLANTS    AND    ANIMALS. 


107 


of  barley.  It  is  probaljly  11  native  of  Cliili  or  Peru, 
but  will  grow  in  Iceland. 

In  the  low,  damp,  and  hot  portions  of  the  equa- 
torial region,  wheat  and  corn  are  replaced  by  rice 
and  the  banana,  mandioca,  and  the  bread-fruit. 

Rice. — The  geographical  range  of  rice  is  limited 
by  the  parallels  of  45°  north  and  35°  south.  This 
belt  covers  more  than  half  the  surface  of  the  earth. 
Kice  delights  in  low  and  swampy  ground,  and  con- 
stitutes in  India  and  China  the  chief  staple  of  cul- 
tivation. It  is  the  princij)al  article  of  food  for 
one-third  of  the  entire  human  family. 

Tlie  Banana,  indigenous  in  the  regions  of  inter- 
troj)ical  Amei-ica,  is,  as  an  article  of  food  for  the 
masses,  what  rice  is  to  tlie  Hindoos,  the  jiotato  to 
the  Irish,  and  wheat  to  the  European.  An  acre  of 
ground  planted  in  bananas  requires  less  cultivation 
and  yields  more  abundantly  than  any  other  food- 
plant.  Humboldt  estimates  the  yield  to  exceed 
that  of  the  jiotato  4-1  times,  and  that  of  wheat  133 
times.  Tlie  banana  flourishes  4,000  feet  above  the 
sea. 

Mandioca  or  Cassava  is  a  native  of  South  America.  It  is 
also  extensively  grown  in  Africa  and  otlier  tropical  regions. 
Its  large  turnip-like  root,  dried  and  grated,  is  the  food  of  a 
large  part  of  the  population  of  South  America. 

Bread  Fruit  is  characteristic  of  the  islands  of  the  Pacific. 
Its  fruit,  represented  in  the  cut,  furnishes  the  natives  with 
food  somewhat  resembling  bread. 

The  Sugar-cane,  so  far  as  we  know  its  history,  seems  to 
have  been  a  native  of  India  or  China.  It  grows  in  the  warm 
latitudes  of  everv  continent. 


cal  range  of  the  spices,  such  as  cinnamon,  nutmeg, 
ginger,  pep])cr,  cloves,  allsjjice,  and  pimento,  is 
narrow.     It  is  confined  to  a  few  degrees  north  and 


BKEAD-FRUIT. 


5.  Beverage  Plants, — The  chief  plants 
which  yield  beverages,  tea,  coffee,  and  cocoa,  are 
grown  in  warm  regions.  Tea  is  mostly  confined 
to  China  and  Japan  ;  coffee  to  Southern  Asia, 
Central  Africa,  and  the  tropical  portions  of  North 
and  South  America.  Cocoa  is  a  native  of  the 
tropical  regions  of  North  and  South  America. 

6,  Spices  and  Narcotics. — The  geographi- 


south  of  the  equator.  The  East  Indies  are  specially 
the  region  of  the  sj)ices. 

The  important  narcotics,  tobacco  and  opium, 
are  natives  of  warm  regions,  but  their  geographi- 
cal range  extends  into  the  temperate  zones. 

7.  Plants  iised  for  Clotliitif/. — The  prin- 
cipal jilants  which  are  used  for  textile  fabrics  and 
clothing  are  cotton,  flax  and  hemp. 

Cotton,  the  most  important  of  them  all,  will 
grow  and  mature  avcU  at  moderate  heights,  any- 
where between  the  ])arallels of  37-2°  north  and  south. 
This  belt  being  75°  of  latitude  broad,  and  extend- 
ing entirely  round  the  earth  where  its  circumfer- 
ence is  largest,  gives  for  this  plant  a  geographical 
range  that  embraces  more  than  half  the  earth's 
surface. 

The  United  States,  Brazil,  India,  and  Egyf)t  are 
the  chief  cotton-growing  countries. 

Flax  and  Jie7nj}  delight  in  the  climates  of  the 
temperate  zone,  and  are  brought  to  their  greatest 
perfection  between  the  parallels  of  25°  and  50' 
north. 

8.  TJte  3£edicinal  Plants,  such  as  yield 
sarsaparilla,  jalap,  castor-oil,  quinine,  gums,  and 
balsams,  are  almost  all  indigenous  to  the  torrid 
zone. 


io8 


RANGE    OF    PLANTS    AND    ANIMALS. 


Foremost  among  them  stands  tlie  cinchona,  from 
which  quinine  is  obtained.  It  is  a  native  of  the 
eastern  slopes  of  the  Andes,  and  of  a  belt  lying  be- 
tween Bolivia  and  Ecuador,  from  3,000  to  9,000 
feet  above  the  sea-level.  It  has  been  successfully 
acclimatized  in  tiie  East  Indies. 

f).  Useful  T/'ee.s.— The  ornamental  and  dye- 
woods,  such  as  mahogany,  rose,  sandal,  and  log- 
wood, are  confined  to  the  torrid  zone.  The  oak, 
walnut,  chestmit,  majile,  ash,  with  pines,  firs,  and 
cedars,  belong  to  the  cooler  latitudes. 

The  geograj)hical  range  of  the  oak  extends  fi-om 
the  tropics  to  the  verge  of  the  frigid  zone.  The 
timber  trees  of  the  temperate  zone  are  replaced  in 
the  torrid  by  the  teak  and  bamboo. 

10.  The  Flora  of  the  ,S'e«.— The  flora  of 
tlie  sea  differs  from  that  of  the  land  in  color.  It 
is  less  inclined  to  green.  The  plants  of  the  sea  are 
brown  and  yellow,  pink  and  purple,  green,  orange 
and  violet,  with  all  intermediate  shades. 

The  vegetation  of  the  sea  has,  like  that  of  the 
land,  a  vertical  and  a  horizontal  distribution. 
Both  are  determined  mainly  by  the  temperature 
of  the  water,  and  the  nature  of  the  sea  bed. 

In  the  deepest  parts  of  the  ocean  nothing  but 
microscopic  forms  of  vegetable  life  of  the  simplest 
kind  (called  diatoms)  occur.  The  smaller  algffi  or 
sea-weeds  scarcely  exist  below  the  depth  of  300 
feet ;  the  larger  are  not  found  deeper  than  about 
60  feet  below  the  surface.  The  horizontal  range 
of  many  marine  plants  is  co-extensive  witli  the  sea. 
Others,  like  land  plants,  have  limited  ranges. 

Alg^. — Among  the  most  interesting  kinds  of 
algae  are  the  Macrocystis  Pyrifera,  the  Du  Willaca 
Utilis,  and  the  Gulf  Weed. 

The  Macrocystis  Pyrifera  measures  700  feet  in  length. 
This  weed  is  like  a  cord.  It  attaches  itself  to  the  rocks, 
and  grows  from  the  bottom  in  the  littoral  waters  of  many 
countries,  and  especially  along  the  northwest  coast  of 
America. 

Few,  if  any,  forms  of  vegetation  have  a  wider  geographi- 
cal range  than  this  weed.  After  all  traces  of  plant  life  on 
the  land  have  ceased,  as  you  approach  the  poles,  it  is  still 
found  flourishing  in  the  water. 

Du  Willaca  Utilis. — In  the  waters  of  the  Falkland  Islands 
there  grows  Du  Willaca  Utilis,  a  vegetable  cable  several 
hundred  feet  long,  and  as  thick  as  the  human  body.  This, 
like  the  Macrocystis  Pyrifera,  fastens  itself  to  the  rocks,  in 
stormy  waters,  with  such  tenacity  that  sometimes,  in  the 
attempt  to  tear  it  away,  large  boulders  are  brought  up  ad- 
hering to  its  roots. 

Plants  of  this  species  sin'round  Kerguelen  Land  with  such 
a  tangled  mass,  that  row-boats  find  it  diflicult  to  get 
through  it.  The  Straits  of  Magellan  are  so  thick  with  these 
weeds  that  they  fouled  the  rudder,  and  so  entangled  the 
propellers  of  the  first  steam  vessels  that  passed  through 
these  waters,  as  seriously  to  interfere  with  the  navigation. 


Oulf  Weed. — Among  the  most  widely  distributed  forms 
of  marine  vegetation  is  the  Gulf  Weed  {fticua  ?iatanii). 
It  is  not  known  whether  it  grows  at  the  bottom,  or  near  the 
surface  of  the  sea.  I  have  always  found  it  afloat,  living  and 
bearing  seed,  but  without  any  sign  of  roots.  It  lies  so  thick 
in  the  Sargasso  Sea,  as  completely  to  hide  the  waters  in  many 
jtlaces  and  give  the  sea  the  appearance  of  a  drowned 
meadow. 

11.  Diatfibution  of  Animals.  —  Ani- 
mals, like  plants,  require  a  certain  temperature, 
tor  the  maintenance  of  their  life.  Furthermore, 
no  animal  except  man  can  inhabit  regions  in 
which  nature  does  not  spontaneously  provide  for 
it  suitable  food  ;  and  hence  the  fauna  of  every 
country  is  dependent  on  its  flora.  For  these  two 
reasons  the  distribution  of  animals,  like  that  of 
plants,  depends  mainly  upon  climate. 


Zones  of  Animal  Life. — In  view  of  this  fact 
it  is  usual  to  divide  the  earth's  surface,  in  relation 
to  its  fauna,  into  the  same  equatorial,  temperate, 
and  polar  zones  which  have  been  indicated  in 
treating  of  the  distribution  of  plants. 

TJie  Equatorial  Zone  is  characterized  by  the 
abundance  of  its  forms  of  animal  life.  It  is  the 
zone  of  lions,  tigers,  rhinoceroses,  elephants, 
camels,  crocodiles,  poisonous  serpents,  and  birds 
of  the  most  brilliant  plumage. 

Tlie  Temperate  Zones,  on  the  other  hand,  are 


RANGE    OF    PLANTS    AND    ANIMALS. 


109 


distinguislied  by  the  number  of  their  useful  ani- 
mals, such  as  the  ox,  cow,  horse,  sheep,  and  goat. 
The  eagle,  turkey,  and  pheasant  are  among  the 
birds.  In  coloring,  tlic  animals  of  temjierate 
regions  are  far  less  brilliant  than  those  of  the 
equatorial  zone. 

In  the  Arctic  rer/ions  (for  of  the  Antarctic  we 
know  little  or  nothing)  we  find  the  fewest  species, 
although  the  individuals  are  numerous.  The 
reindeer,  musk  ox,  white  and  brown  bear,  wolves, 
white  foxes,  and  sables  are  the  chief  land  animals. 
The  seal,  walrus,  and  whale  sport  in  the  waters. 
Reptiles  are  unknown. 

Zoological  Eegions. — It  is  obvious  that  any 
division  of  the  earth's  surface  into  zones  charac- 
terized by  peculiar  fauna  and  flora  is  necessarily 
far  from  exact.  Although  the  distribution  of  life 
on  the  globe  is  mainly  dependent  on  climate,  it  is 
not  so  altogether. 

For,  in  the  first  place,  many  species  over-lap, 
being  found  in  more  than  one  zone.  The  dog  is 
the  companion  of  man  in  every  zone  ;  sugar-cane 
grows  in  both  torrid  and  temperate  regions. 

And  in  the  second  place,  however  alike  in  cli- 
mate different  portions  of  the  earth's  surface  may 
be,  they  do  not  necessarily  have  the  same  flora  and 
fauna.  The  isothormals  of  the  United  States 
traverse  also  the  Empire  of  China.  Yet  there 
are  marked  differences  between  the  forms  of  plant 
and  animal  life  which  characterize  the  two  regions. 
The  isothermal  of  G8°  i)asses  through  Australia, 
South  America,  China,  and  the  Gulf  region  of  the 
United  States.  But  the  vegetation  and  animal 
life  of  these  regions  are  strikingly  diverse. 

From  these  considerations  scientific  men  liave 
been  led  to  seek  some  division  more  in  luirmony 
than  that  of  zones  with  existing  facts.  That  jiro- 
posed  by  the  eminent  naturalist  Sclater,  and  more 
exactly  defined  by  Mr.  AVallace,  seems  to  be  the 
most  satisfactory  thus  far  devised. 

According  to  this  division  the  surface  of  the 
earth  is  made  up  of  six  regions.  Each  of  these 
has  certain  forms  of  life  which  arc  peculiarly  its 
own  and  not  found  elsewhere,  although  it  may 
have  many  sjDccies  in  common  with  other  regions. 
The  following  are  the  names  of  the  regions  with 
their  leading  characteristic  forms.  [See  map  on 
next  page.  ] 

(1)  The  Northern  Old  World  Region  includes 
all  of  Europe,  all  temperate  Asia  north  of  the 
Himalayas-  and  northern  Africa  down  to  the 
Tropic  of  Cancer.  Here  we  find  the  bear,  wolf, 
deer,  horse,  cow,  and  camel,  tlie  wild  goats,  the 
eagle,  the  corncrake,  and  l)ustard. 

Peculiar  to  this  region  are  almost  fill  the  known 
species  of  goats   and  sheep,  moles  and   dormice ; 


and   among  birds  the  nightingale,  magpies,  and 
almost  the  entire  grouji  of  pheasants. 

(2)  The  Ethiojnan  or  African  Region  embraces 
Africa  soutli  of  the  Tropic  of  Cancer,  southern 
Arabia,  and  the  island  of  Madagascar.  Here  we 
lose  sight  of  certain  forms  familiar  in  the  North- 
ern Old  World  Eegion,  bears,  deer,  moles,  and 
true  pigs ;  and  camels  and  goats,  except  in  the 
desert  regions,  are  equally  wanting. 

Peculiar  forms  are  the  gorilla,  chimpanzee  and 
baboon,  the  hippopotamus  and  giraffe,  the  guinea- 
fowls,  mest  of  the  weaver  birds,  and  the  secretary 
bird. 

Madagascar  and  the  neighboring  islands,  though  classed 
as  parts  of  the  Ethiopian  region,  have  a  fauna  peculiar  to 
themselves.  This  insular  sub-region  is  one  of  the  most 
wonderful  in  the  world  from  a  zoological  point  of  view.  It 
is  especially  characterized  by  the  abundance  of  lemurs  (noc- 
turnal animals  somewhat  resembling  monkeys,  but  very 
small)  ;  while  most  of  the  groups  in  which  Africa  is  especi- 
ally rich — apes,  lions,  leopards,  giraffes,  antelopes,  and 
elephants — are  wholly  wanting.  Some  of  the  birds  are  en- 
tirely unlike  aU  other  known  species. 

(3)  Tlie  Indian  Region  comprises  India,  Indo- 
China  and  the  East  Indian  Islands  as  far  as  the 
Strait  of  Macassar. 

Peculiar  to  this  region  are  the  ourang-outang, 
the  tiger,  the  honey-bear,  the  civet  and  flying  le- 
murs ;  and  among  the  bright-feathered  birds,  the 
argus  pheasant,  the  peacock,  tlie  trogou,  and  the 
curious  little  tailor  birds. 

(4)  The  Australian  Region  consists  of  Austra- 
lia, New  Zealand,  Polynesia,  and  those  of  the 
Malayan  islands  that  lie  cast  of  the  Strait  of  Ma- 
cassar. 


AUSTRALIAN    ANIMALS. 


This  region  has  a  fauna  of  marked  peculiarity. 
It  is  notable  for  the  ab.scnce  of  forms  elsewhere 
almost  universally  diffused.  The  higher  mam- 
malia of  other  regions  are  replaced  by  various 
species  of  marsupial  animals  (that  is,  animals 
provided  with  a  pouch  for  holding  their  young). 


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112 


RANGE  OF  PLANTS  AND  ANIMALS. 


Questions  on  the  Chart  of  Animals. — Into  how  many 
regions  of  animal  lite  is  tlie  surface  of  the  earth  divided  on 
the  map  ?  Of  what  does  oafh  consist  ?  Of  what  regions  is 
the  reindeer  an  inhabitant  ?  Where  is  the  moose  deer 
found  ?  Describe  the  limits  of  the  Polar  bear.  What  other 
animals  are  in  the  North  Frigid  Zone. 

What  fur-bearing  animals  are  found  in  \orlh  America  ? 
In  Europe  and  Asia  ?  Arc  the  fur-bearing  animals  found 
in  cold  or  in  warm  countries  ? 

What  are  the  limits  within  which  monkeys  are  found  ? 
To  what  regions  do  they  belong  ?  Wliero  are  baboons 
found  ?  Describe  the  limits  of  the  elephant  and  rhinoceros. 
Of  the  royal  tiger.  Of  the  camel.  To  what  regions  do  they 
belong  ? 

Where  are  gorillas  found  ?  Porcupines  ?  Yaks  1  Hip- 
popotamuses ?  Walruses  ?  Seals  ?  What  animal  is  pecu- 
liar to  the  Australian  region  ? 

Describe  the  limits  of  tlie  sperm  whale  ;  the  right  whale. 
What  are  the  limits  of  crocodiles  ?  Mention  tlie  localities 
in  wliieh  the  cod  is  found.     The  mackerel.     Shark. 

Where  are  pearl  oysters  found  ?  In  warm  or  cold  waters  ? 
Are  the  seal  and  the  walrus  found  in  cold  or  in  warm  water  ? 

What  are  the  limits  of  the  nightingale  ?  Of  the  eider- 
duck  ?  Of  humming-birds  ?  Of  parrots  ?  To  what  regions 
do  they  belong  ?     [See  small  map.] 

Does  the  duck  seem  to  be  a  native  of  low  or  of  high  lati- 
tudes ?  How  is  it,  in  this  respect,  with  the  albatross  ?  The 
gull  ?  Is  the  mocking  bird  a  native  of  warm  or  of  cold 
latitudes  ?    The  ostrich  ?    The  bird  of  paradise  ? 


Of  these  none  are  found  elsewhere,  except  the 
opossum  of  Nortli  and  South  America.  Among  the 
marsuiiiiils  of  Atistralia  are  the  kangaroo,  the  tree- 
kangaroo,  and  the  wombat.  The  duckbill  is  found 
nowhere  else. 

The  bird  life  of  this  region  is  rich  in  handsome 
and  peculiar  forms,  such  as  the  beautiful  bird  of 
paradise,  the  crimson  dory,  the  lyre  bird,  the 
bower  bird,  the  emu,  and  the  cassowary. 

(5)  The  North  American  Region  includes  the 
continent  and  adjacent  islands  north  of  the  Tropic 
of  Cancer. 

The  fauna  of  this  area  and  that  of  the  Old 
World  region  present  marked  dissimilarities. 
Here  we  do  not  find  native,  the  horses,  asses, 
cows,  sheep,  pigs,  hedgehogs,  and  dormice  of  the 
Old  World.  They  are  replaced  by  the  bison,  rac- 
coons, opossums  (marsupial),  prairie  dogs  and 
skunks.  The  tlirushcs,  wrens,  robins,  and 
finches  are  represented  by  new  families. 

Among  animals  peculiar  to  this  region  are  the 
grizzly  bear,  the  pouched  rat,  the  mocking-bird, 
the  blue-jay,  the  blue  crow  and  the  rattlesnake. 

It  is  hardly  necessary  to  say  that  many  Old 
World  forms  have  been  introduced. 

(0)  The  South  American  Region  embraces  South 
America  and  that  portion  of  North  America  and 
the.  outlying  islands  which  are  south  of  the  Tropic 
of  Cancer. 

Of  all  the  regions  this  is  the  most  remarkable 


for  the  fewness  of  the  forms  wliich  it  contains  in 
common  with  others.  No  horse,  or  ass,  ox,  sheep 
or  goat  is  a  native  of  South  America.  The  wild 
cattle  and  liorses  which  now  roam  over  its  jjlains 
and  pampas  are  the  offspring  of  animals  introduced 
by  Europeans. 

Tbis  region  is  equally  remarkable  as  containing 
a  greater  number  than  any  other  of  forms  ■which 
are  strictly  its  own.  Among  these  are  the  sloth, 
the  armadillo,  the  llama,  tlie  alpaca  and  chin- 
chilla, the  blood-sucking  vampire  bat,  the  prehen- 
sile-tailed monkey,*  and  the  destructive  boa-con- 
strictor. 

Here  alone  we  find  the  condors,  toucans,  todies, 
rheas,  curassows  and  mot-mots.  The  forest-clad 
slopes  of  the  Andes  are  alive  with  the  murmur  of 
400  species  of  humming  birds,  some  of  which  pass 
their  cheery  existence  near  the  limits  of  perpetual 
snow. 


12.  Bnnge  of  Dvauyht  Aninialx.—Oi 

special  interest  is  the  geographical  range  of  those 
animals  which  man  employs  as  draught  animals  or 
beasts  of  burden. 

The  horse,  the  ass  and  the  ox,  cither  native  or 
introduced,  are  found  wherever  grains  and  grasses 
grow.  Beyond  the  limits  of  these  food  plants  the 
reindeer  and  the  dog  become  the  draught  animals. 
The  reindeer  is  fitted  to  browse  upon  Arctic  mosses, 
and  has  the  instinct  of  searching  for  them  beneath 

*  Monkeys  wlioso  tnils  are  capable  of  grasping  the  branches  of  trees. K 


RANGl",    OI'    PLANTS    AND    ANIMALS. 


"3 


the  snow.  He  presents  one  of  the  most  striking 
cases  of  an  animal  adapted  to  the  peculiar  condi- 
tions of  his  habitat. 

In  the  equatorial  regions  of  tlie  Old  World  we 
find  tlio  elephant  serving  as  a  beast  of  burden ; 
while  to  the  nortliward,  especially  in  desert  regions, 
the  camel  and  dromedarj-  are  employed. 

The  cusliioned  foot  of  the  camel  enables  him  to  tread 
firmly  upon  the  shifting  sands  of  the  desert,  while  his  ca- 
jiacity  for  carrying  an  extra  supply  of  water  adapts  him 
wonderfully  for  journeying  througli  its  dry  and  thirsty 
wilds. 

In  South  America,  where,  to  traverse  the  conti- 
nent, the  traveller  lias  to  scale  the  snowy  heights 
of  the  Andes,  there— and  not  in  Xorth  America, 
where  the  mountains  have  gaps  that  the  buffalo 
can  cross — was  found  the  llamn,  the  camel  of  the 
Nev/  World,  the  only  beast  of  burden  in  use  among 
the  native  Americans  at  the  time  of  the  discovery 
of  the  continent. 

The  llama,  with  the  alpaca  and  vicuna,  which  are  differ- 
ent species  of  the  same  genus,  have  their  habitat  along  the 
edge  of  the  snow-line  on  the  Andes,  where  the  atmospheric 
pressure  is  not  more  than  eight  or  ten,  instead  of  fifteen, 
pounds  to  the  square  inch. 

This  diminished  pressure  of  the  atmosphere  has  very 
marked  effects  upon  both  man  and  beast.  To  one  from  (he 
lowlands,  respiration,  in  these  elevated  regions,  is  difficult. 
Mules  are  used  for  the  transportation  of  merchandise  between 
these  places  and  the  seaboard,  but  never  ascend  beyond  a 
certain  height.  At  the  elevation  of  5,000  or  0,000  feet  they 
are  met  by  tlie  llamas  of  the  table-land,  and  the  cargoes  are 
exchanged. 

The  same  wise  provision  appears  in  the  organization  of 
tlie  llama  as  in  that  of  the  camel.  Without  tlicse  creatures, 
man,  in  the  early  stages  of  civilization,  could  neither  have 
crossed  the  deserts  of  the  Old  World,  nor  scaled  the  eloud- 
capped  mountains  of  the  New. 

Among  the  fastnesses  of  the  Himalayas,  and  upon  the 
bleak  heights  of  the  plateau  of  Thibet,  the  beautiful  yak 


serves  as  a  beast  of  burden.  He  is  to  be  seen  browsing  at 
an  elevation  of  1!),;^00  feet  above  the  sea.  What  the  camel 
is  to  the  AraVi,  what  the  llama  was  to  the  Peruvian,  the  yak 
is  to  the  native  of  Thibet. 


Hi.  Limited  Jtmuje  of  Some  Ani- 
mals.— Many  animals  are  confined  to  a  very 
narrow  gcograjiliical  range  by  causes  tliat  are  in 
some  cases  quite  obscure.  The  little  chincliilla, 
with  its  beautiful  fur,  has  its  habitat  on  the  Boliv- 
ian Andes,  15,000  feet  above  the  sea. 

The  chamois  inhabits  the  belt  of  the  Alps  which 
lies  between  the  trees  and  the  snow-line. 

Tlie  Cashmere  goat,  noted  for  its  fine  wool,  is 
restricted  to  the  valleys  of  the  Himalayas. 

The  ostrich  of  Africa,  the  rhea  of  South  Amer- 
ica, the  emu  of  Australia,  tlie  cassowary  of  Java, 
the  apteryx  of  New  Zealand,  the  dodo  of  Mauri- 
tius, the  epiornis  of  ^Madagascar,  are 
birds  which  can  neither  fly  nor  swim, 
and  their  geographical  range  therefore 
is  exceedingly  limited. 

Animals  of  limited  range  are  tlie 
most  lil-ehj  to  lecome  e.dincf.  Tlie 
apteryx  is  nearly  so  ;  the  dodo  has 
,/  ;_  become  so  within  the  memory  of  man  ; 
and  the  epiornis  became  so  at  no  very 
remote  period,  for  the  sliells  of  its 
broken  eggs  have  been  found  on  its 
native  island. 

Of  all  animals,  perhaps,  none  has  its  geo- 
graphical range  so  singularly  marked  as  the 
Tsetse  fly  of  South  Africa.  Though  it  is  well 
formed  for  flight,  it  never  appears  to  go  be 
yond  certain  limits.  These  are  marked  by  no 
river,  hills,  or  other  geographical  feature,  and 
yet  are  so  sharjily  defined  by  their  invisible 
boundaries,  that  if  a  horse  crosses  them,  he  is 
immediately  attacked  by  the  fly  and  killed. 


114 


RANGE    OF    PLANTS    AND   ANIMALS. 


14.  Fauna  of  the  Sen. — As  with  the 
animals  of  the  land,  so  with  tliose  of  tlie  sea — 
different  species  have  their  geographical  range, 
botli  vertical  and  horizontal,  bevond  the  limits  of 


which  the  conditions  necessary  for  their  existence 
are  not  found.  This,  however,  is  less  rigidly  true 
with  regard  to  the  fauna  of  the  sea  than  that  of 
the  land.  It  is  quite  obvious  that  temperature  must 
be  the  main  element  which  determines  the  habitat 
of  marine  animals.  Other  matters,  such  as  the 
nature  of  the  sea-bottom,  have  a  minor  influence. 

Life  of  Tropical  AVaters. — The  waters  of 
the  tropics,  like  the  shores  which  they  bathe,  teem 
with  the  greatest  variety  of  animal  forms.  Many 
of  the  fish  and  crustaceans  are  decked  with  colors 
of  surprising  brilliancy. 


OTSTKBS   OP    DIFFERENT    AGES. 


are  all  inhabitants  of  intertropical  seas.  Pearl- 
oysters,  also,  with  corals  and  sponges,  are  found  in 
this  belt. 

Life  of  Cooler  Waters. — In  the  cooler  seas  of 
the  temperate  and  arctic  regions  we  find  the  greatest 
abundance  of  fish  that  are  of  value  to  man.  All 
the  famous  food-fisheries  in  the  world — those  of 
the  cod,  the  herring,  the  mackerel,  and  others — 
are  in  the  waters  of  cold  currents. 

The  Grand  Banks  of  Newfoundland,  the  fisheries  of  the 
North  Sea,  and  tliose  of  the  Pacific  coasts  of  America, 
China  and  Japan,  all  lie  within  the  range  of  the  cold  flow 
from  the  north.  It  is  to  the  presence  of  the  cold  current 
along  our  Atlantic  seaboard  that  our  own  fish  markets  owe 
their  celebrity. 

The  right  whale  delights  in  the  cold  waters  of  polar  seas. 
Those  of  the  torrid  zone  are  as  impassable  to  him  as  a  sea 
of  flame.  So  true  is  this  that  the  right  whale  of  the  north- 
ern hemisphere  and  the  right  whale  of  the  southern  are 
restricted  each  to  his  own  zone. 


The  sperm  whale  delights  in  the  warm  waters  of 
this  zone,  and  is  most  abundant  in  the  Pacific 
Ocean.     Flying-fish,  albacore,  bonito  and  sharks 


MARBLED    SEAL, 

Although  the  seal  may  be  found  in  all  latitudes,  his  fa- 
vorite haunts  are  the  islands  of  Alaska,  the  shores  of  Lab- 
rador and  the  bays  of  Patagonia.  Other  inhabitants  of 
polar  waters  are  the  sea-lion,  hunted  for  his  fur,  and  the 
walrus,  for  his  ivory  tusks,  which  are  superior  to  those  of 
the  elephant,  and  the  narwhal,  or  sea  unicorn,  whose  ivory 
horn  is  eight  or  ten  feet  in  length. 

Various  depths  are  suited  to  various  species  of  marine 
animals.  The  reef-building  polyp  cannot  flourish  at  a 
greater  depth  than  about  150  feet  below  the  surface.  Lower 
down,  in  depths  so  great  as  1,500  or  even  3,000  fathoms, 
living  forms  are  found,  but  they  are  of  a  low  order — sili- 
cious  sponges,  starfishes,  molluscs  (oysters,  etc.)  and  fora- 
minifera. 

lo.  Floral  Serf  ions. — What  may  have  been 
in  all  cases  the  precise  causes  which  led  to  the 
existing  distribution  of  animal  life  is  not  merely 
diflicult,  but  impossible  to  decide.  No  doubt  the 
reasons  for  the  absence  from  South  America  of 
every  kind  of  native  horse  or  ass,  and  the  presence  of 
many  jjeculiar  forms  of  life,  must  be  sought  in  the 
long  past  geological  history  of  the  continent.  To 
a  large  extent  they  must  he  forever  matter  of  con- 


RANGE  OF  PLANTS  AND  ANIMALS. 


"5 


jecture  ;  and  the  same  may  be  said  of  many  other 
exceedingly  curious  problems  that  present  them- 
selves to  the  student  of  tiiis  subject. 

But  whatever  the  causes  in  question  may  have 
been,  we  should  naturally  expect,  from  the  intimate 
connection  of  plant  and  animal  life,  that  the  influ- 
ences which  have  affected  the  distribution  of  the 
one  should  have  produced  a  corresponding  effect 
upon  the  other.  In  a  word,  it  would  seem  reason- 
able that  the  six  regions  into  which  the  earth's 
surface  has  been  found  to  be  divisible  on  zoological 
grounds  should  be  not  only  zoological,  but  pliyto- 
logical  or  botanical  also. 

The  flora  of  each  region  may  not  perhaps  be  as 
distinctly  marked  as  the  fauna.  There  will  nat- 
urally be  much  overlapping,  many  species  being 
very  widely  diffused,  and  some  being  common  to 
all  parts  of  the  globe.  Still  we  ought  to  find 
some  characteristic  floral  peculiarities  in  each 
region.     And  this  we  do  find. 

The  Old  World  region  is  the  native  home  of 
wheat,  the  apricot,  the  cherry,  the  a^sple  and  jjear, 
the  olive,  the  cork  oak,  and  sycamore  fig. 

The  Ethiopian  region  has  among  its  peculiar 
vegetable  forms  the  baobab,  the  oil  palm,  and 
coffee. 

The  Indian  region  is  characterized  by  the  ban- 
yan, the  fig,  the  mango,  cinnamon,  the  gutta- 
percha and  teak  trees,  and  the  sweet  potato. 

The  Atistralian  region  has  a  flora  very  distinct 
from  that  of  all  others.  The  leaves  of  the  trees 
are  of  a  peculiar  bluish-green  hue,  and  strangely 
present  their  edges  to  the  sun,  arranging  them- 
selves vertically  instead  of  horizontally.  The 
eucal3rptus  or  gum-trees,  of  which  there  are  400 
varieties,  and  which  have  the  singular  property  of 
shedding  their  bark  annually  instead  of  their 
leaves,  and  the  New  Zealand  flax,  are  strikingly 
peculiar. 

The  North  American  region  is  the  native  home 
of  the  magnolia,  the  live  oak,  the  sequoia  gigantea 
(giant  trees  of  California),  and  iiersimmon.  Nearly 
400  species  of  trees  are  peculiar  to  this  region. 

The  South  American  region  is  distinguished  by 
the  multitude  of  its  parasitic  forms.  Peculiar  to 
it  are  the  cinchona,  cacao  and  cocoa,  the  mandioc, 
the  potato,  sarsaparilla,  the  Victoria  Regia,  and  the 
passion  flower. 

TOPICAL   ANALYSIS. 
n.    RANGE   OF   PLANTS   AND   AJ*IMALS. 

1.  General  facts. 

Illustrations.    Geographical  range. 

3.  Range  dependent  on  Climate. 


Illnstrations  furnished  by  geology.  Modificatioiu 
by  climate.    Indian  corn. 

3.  Zones  of  Vegetation. 

How  defined. 

Horizontal  zonc^.  Limits  and  characteristics  of 
each. 

Vertical  zones.  Correspondence  of  their  charac- 
teristic vegetation  to  that  of  the  horizontal  zones. 

4.  Bange  of  Food  Plants. 

Kange  of  cereals;  barley,  rye,  wheat,  Indian  corn, 
millet  and  rice.  Of  the  potato,  banana,  mandioca, 
bread- frnit  and  sugar-cane. 

5.  Beverage  Plants. 

6.  Spices  and  Narcotics. 

7.  Plants  used  for  Clothing. 

8.  medicinal  Plants. 

9.  TTsefnl  Trees. 

Timber  trees  of  I  he  torrid  zone. 

10.  Flora  of  the  Sea. 

Colors,  as  compared  with  those  of  the  laud  flora. 
Distribution.    Vertical  distribution. 
Algi3e.    Interesting  forms. 

11.  Distribution  of  Animals. 

Why  mainly  dependent  on  climate. 

Zones  of  animal  life.    Characteristics  and  principal 

animals  of  each. 
Zoological  regions.    Divisions  into  zones  of  life. 

why    not   exact.      Animal  life  of  the    different 

zoological  regions,  to  what  extent  distinct. 
Northern  Old  World  region.     Important  animals. 

Animals  peculiar  to  the  region. 
Ethiopian  region.     Peculiar  forms,    .\niraal  life  of 

Madagascar  and  neighboring  islands. 
Indian  region.     Peculiar  animals. 
Australian  region.     For  what  remarkable.    Forms 

peculiar  to  it. 
North  American  logion.    Distinction  between  its 

forms  and  those  of  the  Northern  Old  World. 

Peculiar  animals. 

South  American  region.  For  what  remarkable 
Peculiar  forms. 

12.  Bange  of  Draught  Animals. 

Adaptation  of  the  reindeer,  the  camel,  and  the 
llama,  alpaca  and  vicuna  to  locality.    The  yak. 

13.  Limited  Bange  of  some  Animals. 

14.  Fauna  of  the  Sea. 

Range  of,  by  what  determined.  Life  of  tropical 
waters.  Of  cooler  waters.  Range  of  the  seal. 
Vertical  range  of  the  reef-building  polyp.  Life 
at  great  depths. 

15.  Floral  Begions. 

Reasons  for  coincidence  of  floral  with  zoological 
regions.    Plants  peculiar  to  each. 

Test  QtrESTioNs.— Name  some  plants  distinguished  for  their  wide 
range.  Some  animals.  Wbat  draught  animals  have  the  widest  range  ? 
Does  tbe  range  of  plants  tend  to  Increase  ?  Of  animals  ?  Is  the  range 
of  either  affected  by  human  agency  ?  Can  you  give  examples  ?  Which 
of  the  cereals  is  produced  in  the  greatest  quantity?  Which  is  most 
largely  raised  in  this  country  ?  Which  has  the  wider  range,  tea  or 
coffee  ? 


ii6 


MAN. 


III.  MAN, 

1.   lianye  of  Human    Habitation. — 

Man  dwells  in  every  zone  and  at  nearly  all  alti- 
tudes. He  is  literally  cosmopolitan.  Unlike  the 
irrational  animals,  he  can,  to  a  large  extent,  over- 
come the  force  of  pxtcmal   conditions.     He  can 


CAI:(A:<1AN    IEAOK. 


protect  himself  from  the  severity  of  the  winter's 
cold,  and  maintain  his  existence  amid  the  snows 
and  icebergs  of  the  Arctic  regions ;  and  on  the 
other  liand  he  can  endure  the  fierceness  of  inter- 
tropical heat.  Thus  liis  horizontal  range  is  almost 
unlimited. 

He  has,  again,  an  ample  vertical  range.  The 
summer  j^asture  of  Larsa,  in  Central  Asia,  is 
16,636  feet  above,  and  the  bottom  of  the  New 
Salzwerk  salt  mines,  in  Prussia,  is  2,280  feet  below 
the  sea-level.  The  lowest  place  where  men  have 
established  permanent  dwelling-i)laces  is  in  the 
valley  of  the  Dead  Sea,  1,300  feet  beloto  the  sea. 
The  highest  is  at  the  convent  of  Hanle,  inhabited 
by  twenty  Thibetan  monks,  16,533  feet  above  the 
sea.  These  limits  include  a  vertical  range  of 
more  than  three  miles. 

2.    TJnitij   of    the  Human  Family. — 

Wherever  man  is  found,  he  presents  the  same 
essential  features  of  body  and  of  mind.  No  such 
differences  sunder  men  as  those  which  subsist  be- 
tween the  horse  and  the  lion,  the  eagle  and  the 
ostrich.     The  human  family  is  of  one  blood. 

li.  Diversity. — Still  the  heat  and  cold  to 
which  man  is  habitually  exposed,  the  food  which 
he  lives  upon,  and  the  physical  conditions  gener- 
ally by  which  he  is  surrounded  will,  in  the  lapse 
of  time,  produce  certain  effects  upon  his  bodily 


and  intellectual  organization.  Hence  we  find 
wide  diversities  characterizing  different  portions 
of  the  human  family. 

Men  differ  in  color,  in  feature,  in  mental  and 
moral  peculiarities,  industrial  habits,  social  and 
governmental  institutions. 

4.  IHvimon  into  Raceft. —  Some  ethnol- 
ogists divide  the  great  human  family  into  three, 
some  into  five,  others  into  six  or  even  a  larger 
number  of  races. 

The  five  great  races  of  mankind,  as  generally 
recognized,  are  the  Caucasian  or  white,  the  Mon- 
golian or  yellow,  the  Negro  or  black,  the  Malay 
or  brown,  and  the  Indian  or  red. 

The  Caucasian  Race  derives  its  name  from 
the  Caucasus  range  of  mountains,  because  of  the 
tradition  that  the  region  traversed  by  these  moun- 
tains was  the  birthplace  of  the  race. 

The  chief  divisions' of  the  Caucasians  are  :  (1) 
the  Indo-European,  com])rising  the  Hindoos,  Per- 
sians, Circassians,  Slavonians,  Teutons,  and  Celts  ; 
and  (2)  the  Semitic  families,  of  whom  the  He- 
brews and  Arabs  are  the  most  imjiortant. 

The  term  Indo-Eiiropcan  is  derived  from  the  fact  that 
this  division  of  the  race  has  established  itself  all  the  way 
from  India  to  the  farthest  bounds  of  Europe. 

Extent. — Seven-eighths  of  the  people  of  the 
United  States,  as  well  as  all  the  peoples  of  Europe, 
except  the  Lapps,  Finns,  and  Magyars,  and  the 
Turks  proper,  belong  to  the  Caucasian  race. 
Both  of  the  Americas  are  governed  by  it.  Africa, 
on   the    Mediterranean,  is   inhabited   bv   it.      In 


MONGOLIAN  RACE. 


Asia,  it  extends  from  the  shores  of  the  Mediter- 
ranean, through  Arabia  and  Persia,  and  along  the 
southern  slopes  of  the  Himalaya  mountains  to  the 
banks  of  the  Brahmapootra. 


MAN. 


117 


Characteristics. — The  Caucasians  are  the  most 
symmetrical  in  figure,  comely  iu  person,  and  beau- 
tiful in  feature,  of  all  the  branches  of  the  human 
family.  Tlie  numerous  divisions  and  sub-divisious 
of  the  race  vary  in  complexion  according  to  the 
region  they  occujiy.  Tlie  extremes  are  the  Ger- 
mans with  their  flaxen  hair,  blue  ej^es,  and  fair 
skin,  and  the  Hindoos  with  raven  locks,  black 
eyes,  and  olive-brown  or  brownish-black  skin. 
The  face  of  the  Caucasian  is  oval,  the  head  ample; 
the  hair  full  and  often  curled  or  wavy. 

Intelhcfual  Superiority. — In  intellect  tliis  race 
ranks  first.  With  very  few  exceptions  all  the 
leading  thinkers  of  the  world  have  been  Cauca- 
sians ;  and  without  any  exception  all  the  great 
.  discoveries  of  i-ecent  times  have  been  made  by 
members  of  this  family. 

It  is  the  race  to  which  lias  been  assis^nerl  the  office  of  civil- 
izing and  enlightening  the  world.  Its  social  habits  and  its 
governmental  institutions,  its  educational  systems,  and  its 
religious  views  are  those  which  most  conduce  to  the  eleva- 
tion and  happiness  of  mankind. 

Wherever  the  white  man  establishes  himself  he  speedily 
becomes  dominant  ;  while  the  communities  of  other  races 
into  which  he  introduces  himself  are  sometimes  subjected 
to  a  gradual  process  of  extinction. 

The  Mongolian  Eace  derives  its  name  from 
the  Asiatic  tribe  of  Mongols.  The  Chinese,  Indo- 
Chinese,  Japanese,  Thibetans,  and  Turks  in  Asia  ; 
the  Finns,  Magyars,  and  Lapps  in  Europe,  and 
the  Esquimaux  of  the  Arctic  regions  of  North 
America  are  branches  of  this  race. 

Characteristics. — The  color  of  the  Mongolian  is 


NEtiKO    RACE. 

olive-yellow.  His  face  is  broad,  with  wide  and 
flattened  nose.  His  hair  is  straight,  coarse,  and 
black.  In  stature  he  is  somewhat  below  the  or- 
dinarv  standard  of  the  Caucasian. 


In  intelligence  and  moral  character  he  ranks 
next  to  the  Caucasians.  The  Japanese  and  Chinese 
branches  of  this  race  have  displayed  marked 
mental  powers,  while  others,  as  the  Esquinuiux, 
are  very  low  in  the  intellectual  scale. 


MALAY    KA<  t. 


Even  the  most  gifted  of  the  race,  with  the  striking  ex- 
ception of  the  Japanese,  are  characterized  by  mental  inac- 
tivity. They  seem  to  remain  just  where  their  ancestors 
were  hundreds  of  years  ago.  The  element  of  progress  is 
wanting  in  their  intellectual  constitution.  Praise  must,  how- 
ever, be  accorded  to  the  Chinese  for  the  development  of  a 
governmental  system  which  has  stood  the  test  of  ages. 

In  religion  the  Mongolians  are  for  the  most  part  follow- 
ers of  Buddha. 

The  Negro  Race  is  so  called  from  the  color  of 
its  skin  (Latin,  nicjer,  black).  It  occupies  nearly 
the  whole  of  the  African  continent.  The  hair  of 
the  Negro  is  short  and  curly  ;  his  nose  is  flat,  wide, 
and  upturned  ;  his  cheek  bones  are  prominent  and 
his  lips  thick. 

The  moral  and  intellectual  status  of  the  Negro 
in  his  native  land  is  low.  When  brought  into 
contact,  however,  with  the  Caucasian  race,  he 
shows  bimsclf  callable  of  no  inconsiderable  eleva- 
tion. 

The  native  Australians,  though  classed  by  some  ethnol- 
ogists as  a  separate  race,  may  properly  be  regarded  as  a 
branch  of  the  Negro  family.  They  are  probably  the  most 
degraded  members  of  the  human  species.  Before  the  Euro- 
pean settler  they  are  rapidly  dying  out. 

The  Malay  Race  is  held  by  some  to  be  a 
branch  of  tlie  Mongolian.  Its  characteristics  are, 
however,  sufficiently  marked  to  render  it  appro- 
priate to  classify  it  separately. 

The  Malays  occupy  a  part  of  Southeastern  Asia 
and  most  of  the  islands  of  the  Pacific.  The  pen- 
insula of  Malacca,  Sumatra  and  Java,  Borneo, 
Celebes,  Formosa,  the  Philippines,  New  Zealand 


ii8 


MAN. 


and  tlic  Polynesian  Islands,  all  hud  this  race  for 
their  aborigines. 

Characteristics. — The  members  of  the  Malay 
race  are  of  medium  height,  with  well-jjroportioned 
limbs.  They  vary  in  color  from  an  olive-yellow  or 
a  brown  hue  to  black.  Their  hair  is  coarse  and 
black. 

Intellectually  and  morally  the  Malayan  is  of  a 
low  order.  In  civilization  he  has  made  hitherto 
little  progress.  Many  of  the  race  are  still  in  the 
lowest  stages  of  savage  life,  although  some  of  theiu 
have  a  written  language  and  a  legal  code.  They 
are  true  sea  rovers,  and  prone  to  piracy. 

The  American  Indians  constitute  what  some 
ethnologists  designate  as  an  ofE-shoot  of  the  Mon- 
golian race.     At  the  time  of  Columbus  thev  had 


AMERICAX    INDIA^JS, 


spread  themselves  all  over  Korth  and  fcjoutli 
America,  from  what  are  now  the  British  posses- 
sions in  the  north  to  Cape  Horn  in  the  south. 

Some  of  the  better  known  tribes  are  the  Chip- 
l)eways,  Sioux.  Apaches,  and  Chcrokees,  in  North 
America  ;  the  Carihs,  the  Araucanians,  and  Pata- 
gonians,  in  South  America. 

CharaderiMics. — The  American  Indian  is  cop- 
])er-colored  or  red,  and  therefore  he  is  often  called 
the  Ked  man.  His  hair  is  black,  coarse  and 
straight,  his  cheek  bones  prominent.  In  person  he 
is  tall  and  lithe.  He  is  remarkable  for  his  endur- 
ance of  fatigue  and  his  disregard  of  pain.  Intel- 
lectually aud  morally  he  occupies  a  medium  posi- 
tion among  the  races  of  mankind. 

The  ludian  is  rapidly  disapjjearing  before  the 
invading  force  of  civilization. 

Early  Civilization  .—The\nca.f,  of  Peru  and  tlie  Aztecs  of 
Mexico  were  found  in  a  comparatively  high  state  of  civiliza- 


tion by  Pizarro  and  Cortez;  and  there  are,  in  Central  Amer-' 
ica  and  the  western  part  of  the  United  States,  interesting 
memorials  of  a  long  forgotten  civilization  which  had  its 
home  in  those  regions. 

The  Montezumas  of  Mexico  had  their  halls,  their  acade- 
mies and  schools,  their  zoological  and  botanieal  gardens, 
their  calendar,  and  their  njonuments.  Their  capital,  at 
the  time  of  Cortez,  \ieA  with  the  wealthiest  cities  of  Europe. 


tioil, — From  this  brief  review  of  the  races  it  will 
be  seen  how  powerful  has  been  the  influence  of 
l^hysical  circumstances  upon  man.  Some  portions 
of  the  human  family  have  remained  hopelessly 
barbarous.  Some  have  received  civilization  from 
others,  and  some,  again,  have  given  birth  to  a 
civilization  of  their  own — an  indigenous  civiliza- 
tion. Wherever  this  last  has  occurred,  it  has  in- 
variably been  neither  at  the  jjoles,  nor  in  the  hot 
lands  of  the  tropics,  but  rather  in  a  middle 
ground  between  the  two.  It  is  here  that  those 
conditions  are  found  which  are  best  adapted  to 
iuan"s  physical  development. 

An  indigenous  civilization  has  never  had  its 
birthplace  under  the  blighting  blasts  of  the  Arc- 
tic regions,  because  there,  from  the  cradle  to  the 
grave,  life  is  one  struggle  for  mere  subsistence.  The 
body  is  so  pinched  and  starved  by  cold  and  hun- 
ger, as  to  prevent  the  develo23ment  of  the  mind. 

Neither  do  the  moist  and  overheated  climates 
of  the  torrid  zone  appear  to  be  favorable  to  mental 
development.  There  the  rainy  season  and  the 
constant  heat  dwarf  and  enervate  the  body. 
Cold  may  not  pinch,  nor  hunger  gnaw,  yet  fever 
racks  the  frame  ;  and  the  mind,  in  its  first  and 
feeble  steps  toward  civilization,  is  crippled  by  the 
ills  of  the  body.  Body  and  mind,  moreover,  lack 
in  the  torrid  zone,  by  reason  of  its  superabundant 
productiveness,  the  great  stimulus  to  human  ex- 
ertion, necessity. 

Man,  to  be  civilized,  must  be  beyond  the  reach 
of  climatic  extremes. 

6*.  Man's  Influence  upon  Physical 
Geography. — While,  however,  we  notice  the 
influence  of  physical  geography  upon  man,  we 
must  also  notice  the  influence  of  man  upon  physi- 
cal geography.  Although,  like  the  brutes,  he  is* 
strongly  impressed  by  his  material  surroundings, 
he  is  unlike  the  brute  creation  in  this  :  thev  can- 


Questions  on  the  Chart  of  Races  of  Men. — Name  the 
regions  occupied  by  the  Caucasians.  The  Mongolians. 
Negroes.  American  Indians.  Malays.  In  how  many  con- 
tinents do  you  find  Mongolians  ?  Caucasians  ?  What  race 
chiefly  occupies  islands  ?  Trace  the  northern  limit  of  per- 
manent inhabitants.  Name  the  chief  articles  of  human 
diet  according  to  latitude.  [See  the  meridian  of  40°  West 
from  Greenwich,  along  which  these  are  given.] 


-  ill 


120 


MAN 


not  modify  the  conditions  which  surround  them  ; 
lie  can.  To  him  alone  has  been  given  authority, 
in  the  language  of  Genesis,  "  to  subdue  the  earth." 

Changes  of  no  small  importance  have  been 
wrought  in  the  aspedt  of  the  earth  by  human 
agency.  These  changes  consist  in  bringing  the 
land  under  cultivation,  in  causing  the  wildomess 
to  blossom,  in  extending  the  range  of  jihmts  and 
animals  that  are  specially  useful  to  man. 

Four  hundred  years  ago  America  was  a  wilder- 
ness, where  wild  beasts  prowled,  and  savage  men, 
clothed  in  skins  and  armed  with  bows,  danced 
their  war-dance.  Contemplating  this  quarter  of 
the  globe  in  its  geographical  aspects  then,  and  be- 
holding it  now,  consider  the  ])otency 
of  human  influence  upon  the  aspect  of 
the  earth. 

In  many  cases  skill  and  iicrseverance 
have  enabled  man  to  triumph  over  nat- 
ural difficulties  that  seemed  almost  in- 
superable. 

D  E  A I  K  A  G  E.  —  No  inconsiderable 
changes  arc  wrought  by  artificial  drain- 
age. Much  of  the  surface  water,  in- 
stead of  being  left  to  form  marshes, 
saturate  the  soil,  and  Ijc  taken  up  l)y 
evaporation,  is  carried  off  underground 
througli  the  drain-pipes  ;  consequent- 
ly, the  air  is  not  so  largely  impreg- 
nated with  moisture  as  formerly,  smd  the  soil,  in- 
stead of  being  constantly  chilled  by  evaporation,  is 
rendered  warm  and  genial. 

This  result  has  been  particularly  noticed  in 
England  and  Scotland,  where  very  extensive  areas 
have  been  artificially  drained. 

Reclamation  of  Land. — Holland  has  been  reclaimed  from 
the  sea.  The  water  has  been  dyked  out ;  and  many  parts 
of  the  country  that  were  the  bottom  of  the  sea  are  now 
dry  land,  and  though  below  the  level  of  the  sea,  form  the 
home  of  industrious  and  happy  communities. 

Years  ago  there  were  along  the  lower  banks  of  the  Mis- 
sissippi, subject  to  overflow,  and  uninhabitable,  "drowned 
lands,"  embracing  an  area  larger  in  the  aggregate  than  the 
State  of  Kew  York.  Many  of  these  lands  have  been  re- 
claimed by  means  of  levees. 

Irrigation. — By  man's  agency  in  using  the 
waters  of  the  Nile  for  irrigation,  Egypt  became  in 
olden  time  the  granary  of  the  world,  and  much  of 
the  country  is  now  made  to  yield  three  crops  every 
year. 

In  India  vast  districts  of  country  are  rendered 
fertile  and  made  habitable  by  the  use  of  tanks  and 
reservoirs,  which  have  been  constructed  for  collect- 
ing the  water  in  the  rainy  season,  and  distributing 
it  in  the  dry,  for  the  purposes  of  irrigation. 

In  the  dry  regions  of  our  own  country  also  sys- 
tems of  irrigation  are  largely  resorted  to.     Es- 


pecially in  Utah,  California,  and  Colorado  the 
wilderness  has  been,  by  this  means,  transformed 
into  a  garden. 

Range  of  Plants  and  Animal.s  Extended. 
— Races  of  men,  species  of  animals,  and  families 
of  plants  have  been  transported  from  one  country 
to  another,  and  their  geographical  range  greatly 
enlarged. 

Indian  corn,  tobacco,  and  the  potato,  witli  many 
other  plants,  the  turkey  and  other  animals,  were 
indigenous  to  America.  They  have  been  carried 
to  other  parts  of  the  world  and  acclimated.  In 
like  manner  the  horse  and  cow,  the  sheep,  hog. 


goat,  ass,  and  other  animals  of  the  Old  World, 
with  the  small  grains  (wheat,  oats,  rye,  barley, 
millet  and  rice),  the  sugar-cane  and  coffee,  with  a 
great  variety  of  other  plants,  have  been  trans- 
ported to  America. 

A  few  stray  sheej],  cattle,  and  horses  escaping  to 
the  pampas  and  llanos  of  South  America,  and  the 
prairies  of  North  America,  have  multiplied  ex- 
ceedingly. Immense  herds  of  them  have  gone 
wild.  So  wonderfully  have  they  increased  that, 
upon  the  pampas,  millions  of  them  are  slaughtered 
for  their  flesh,  hides,  horns,  and  tallow. 

TOPICAL  analysis. 


1.  Sange  of  Human  Habitation. 

Vertical  range. 

2.  Unity  of  Human  Family. 

3.  Diversity. 

Causes. 

4.  Division  into  Races. 

The  Caucasian  race.  Origin  of  name.  Divisiona 
Extent.    Characteristics.    Superiority. 

The  Mongolian  race.  Characteristics.  Non-pro- 
gressive character. 

The  Negro  race.  Why  so  called.  Extent  and  char- 
acteristics. 


GEOGRAPHICAL   DISTRIBUTION    OF   LABOR. 


121 


The  Malay  race.    Extent.    Characteristics. 
American    ludiaiis.      Extent.      Important   tribes. 
CIiaracteriBtics.    Former  civilization. 

5.  Conditions  favorable  to  Civilization. 

Frigid  and  torrid  climates,  wliy  unfavorable. 

6.  Man's  Influence  on  Physical  Geography. 

Extent  of  influence.  Drainage.  Reclamation  of 
land.  Irrigation.  Range  of  plants  and  animals 
extended. 

Test  Questions.— now  is  it  that  man  has  a  wider  range  than  any 
other  animal  ?  If  we  wished  to  divide  the  human  fnraily  into  three 
races  onlj',  how  should  the  division  be  made  ?  To  what  race  do  the 
Moors  belong  ?  The  Siamese  ?  Tlie  Hungarians  ?  The  Hottentots  'I 
The  Fijians  ?  The  Sandwich  Islanders  ?  The  Celts  ?  The  Slavs  ? 
The  Tartars  ?  The  Bedouin  ?  The  Teutons  ?  The  Choctaws  1  The 
Aleutians  ?  The  Pawnees  ?  Do  you  know  of  any  important  exception 
to  the  general  non-progressiveness  of  the  Mongolian  race  ?  Name 
some  respects  in  which  all  the  races  except  the  Caucasians  resemble 
each  other. 

IV.     GEOGEAPHICAL    DISTRIBUTION   OF 
LABOE. 

i.  Distribution  of  Labor  Dcjfcntleiit 
oil  l*7n/sical  Geoffvaphy. — Every  nation  has 
industries  peculiar  to  itself.  These,  to  a  large  ex- 
tent, have  their  root  in  geographical  circumstance, 
or  in  difference  of  climate. 

To  show  how  human  labor,  wlien  nnaSected  by 
tariffs  and  untrammelled  by  legishition,  would 
naturally  distribute  itself  over  the  earth  in  obedi- 
ence to  geographical  law,  let  us  supjjose  two  fami- 
lies to  have  been  planted  originally  on  the  earth, 
one  at  the  equator,  the  other  in  the  Arctic  re- 
gions. How  different,  on  account  of  their  geo- 
gi'aphical  surroundings,  would  be  their  occupa- 
tions ! 

The  intertropical  family  would  seek  the  shades 
of  the  groves,  pluck  the  rijie  fruit  overhead,  re- 
quire little  clothing,  and  be  exem^jt  from  under- 
going the  hardships  of  toil  to  earn  their  daily 
bread.  With  little  exertion  on  their  part  nature 
would  supjily  their  wants. 

The  Arctic  fiimily,  on  the  contrary,  would  be 
clothed  with  skins  and  furs  ;  the  earth  would  pro- 
duce no  grain  or  vegetables  for  them.  They 
would  live  by  the  chase  and  the  bounties  of  the 
sea. 

Diversified  Industries  in  Middle  Lati- 
tudes.— Now,  suppose  these  two  families  grad- 
ually to  extend  themselves,  the  one  toward  the 
north,  the  other  toward  the  south,  meeting  mid- 
way near  the  isotherm  of  50'.  [See  map,  pp.  73,  73.] 

The  occupations  of  both,  as  they  continued  to 
ajiproach  this  middle  ground,  would  no  longer  be 
directed,  on  one  side  mainly  toward  the  sea,  and 
on  the  other  exclusively  to  the  soil ;  but  would  be- 
come more  and  more  diversified. 

'J'lie  necessities  of  the  southern  family  would 
comiiel  them  to  resort  to  sundry  active  occupa- 


tions, some  to  the  manufacture  of  clothing,  others 
to  the  fabrication  of  implements  for  husbandry; 
others  again  to  seafaring.  Novel  opportunities 
would  present  themselves  to  the  northern  com- 
munity, and  induce  them  likewiiBO  to  subdivide 
their  labor.  They  would  divert  a  portion  of  it 
from  the  sea  and  the  chase,  and  devote  themselves 
to  a  greater  or  less  extent  to  agriculture,  to  the 
forest,  the  mine,  and  the  factory. 

Such  a  diversity  of  occupation  really  exists  among 
men.  The  middle  latitudes,  embracing  regions 
lying  not  far  from  the  isotherm  of  50°,  form  a 
belt  encircling  the  earth,  where  human  occupations 
are  most  diversified.  In  some  parts  of  this  belt 
the  tending  of  flocks  and  herds  and  the  raising  of 
stock  are  the  chief  industrial  pursuits  ;  in  other 
parts  agriculture,  in  others  mining,  manufacturing, 
seafaring  and  lumbering  ;  in  some,  all  of  these 
occupations,  or  several  of  them,  are  combined. 

As  you  go  south  of  this  middle  ground,  the  at- 
tention of  the  people  is  devoted  more  and  more  to 
the  field  and  the  forest  ;  and  as  you  go  north, 
more  and  more  to  hunting  and  the  sea. 

Turn  your  eye  along  this  middle  gi-ound  round 
the  world,  and  you  will  find  within  it  the  most 
active  seafaring  and  commercial  peoples  in  the 
world,  the  greatest  manufacturing  nations,  and 
the  largest  cities. 

In  America  the  United  States  for  the  most  pai-t 
is  embraced  within  this  belt.  In  Asia,  Japan  and 
l^arts  of  China,  with  their  large  cities,  are  included 
in  it ;  while  all  the  great  commercial,  manufac- 
turing, mining  and  seafaring  communities  of  Eu- 
rope re.side  within  it. 

You  can  now  i3erceive  that  there  are  geographi- 
cal reasons  why  the  people  of  South  America,  ot 
Africa,  India  and  of  the  tropical  and  sub-tropical 
regions  of  the  earth  should,  in  the  main,  be  rather 
agricultural  or  mining  in  their  industries  than  sea- 
faring or  manufacturing. 

General  Rule. — And  in  general  it  may  be 
laid  down  as  .a  rule  ;  that  the  industries  of  every 
country  are  connected  with  its  geography,  and  that 
human  labor  is  distributed,  largely,  in  obedience  to 
certain  physical  conditions. 

2.  Industries  of  our  own  Country. — 

A  brief  survey  of  the  industries  of  our  own  coun- 
try will  serve  well  to  illustrate  this  law  of  the 
geographical  distribution  of  laljor. 

Agricultural  Pursuits. — Let  us  observe  in 
the  first  place  how  the  principle  a])plies  to  our  va- 
rious agricultural  pursuits.  Climate,  of  course, 
furnishes  the  predominant  reason  why  different 
products  are  raised  in  different  ))art.s  of  the  country. 
But  we  shall  notice  that  other  minor  causes  are 
not  without  their  influence. 


ENGRAVCO  roR  MAURVS 


Questions  on  the  Principal  Industrial 
Pursuits. 

(The  pupil  will  find  this  chart  with  its  abundant  in- 
tormation  well  repaying  extended  study.) 

Name  some  of  the  leading  products  aud  occupations  of 
Great  Britain.  Of  France.  Italy.  Sweden.  Norway. 
Russia,      Germany.      Of  South   Africa.      Madagascar. 


The  Guinea  Coast.   Soudan.    Of  Arabia.    Persia.    India. 

Mention  the  leading  occupations  of  British  America. 
Of  the  United  States  in  different  localities.  Of  Central 
America  and  the  West  Indies.  Of  Mexico.  Brazil.  Peru. 
Chili. 

(Let  the  teacher  examine  pupils  respecting  the  occu- 
pations of  other  countries.) 

What  are  the  employments  of  the  inhabitants  of  Poly- 


U^iyv  >4  V»\\\«i  J  AMirtiT.S.X 


nesia  ?  What  mining  in  New  Caledonia  ?  In  New  Zea- 
land ? 

In  what  part  of  Australia  is  the  mining  district  ? 
What  are  the  occupations  of  the  south-western  portion  ? 

Mention  the  several  regions  of  the  globe  in  which  the 
hunting  and  trapping  of  fur-bearing  animals  is  a  lead- 
ing occupation. 

What  goods  are  manufactured  in  Japan  ?    In  China  ? 


Name  some  regions  where  whale  fishing  is  carried  on. 
Seal  fishing. 

Trace  the  various  routes  for  sea-going  vessels.  From 
San  Francisco,  what  two  routes  to  Japan  and  Hong-Kong? 
To  Sydney?    What  two  to  New  Zealand  ? 

Trace  the  routes  from  the  Indian  Ocean  to  New  York. 
Prom  Bay  of  Bengal  to  Liverpool,  via  Suez  Canal.  Prom 
New  Yorli  to  Australia  via  Isthmus  of  Panama. 


124 


GEOGRAPHICAL    DISTRIBUTION  OF    LABOR. 


The  Mississippi  Valley. — In  the  Valley  of  the 
Mississipjji,  which  may  be  regarded  as  the  great 
agricultural  region,  we  find,  as  we  advance  north- 
ward from  Louisiana,  a  succession  of  climatic 
belts,  and  a  corresponding  succession  of  crojis  en- 
gaging the  attention  of  the  husbandman. 

First  of  all,  near  the  borders  of  the  Gulf  of 
Me.xico,  comes  a  belt  in  which  the  jiroduction  of 
sugar  and  the  culture  of  oranges,  lemons  and  even 
pineapjiles  constitute  leading  branches  of  industry. 
Leaving  thig  belt,  we  enter  regions,  one  after  an- 
other, specially  ada])ted  to  the  cultivation  of  cot- 
ton, tobacco,  corn  and  wheat,  hemp,  the  grape, 
and  orchard  fruits. 

The  Atlantic  Slope. — If  the  journey  lie  along 
the  Atlantic  Slojie  from  Florida  to  Maine,  we  find 
a  similar  succession  of  belts  and  products  ;  but 
with  this  striking  difference,  owing  to  the  infl^u- 
ence  of  the  sea,  viz.,  that  the  climates  are  milder 
and  the  belts  broader. 

In  the  "  Tide-water  Country"  these  belts  are  so 
widened  that  rice  cultivation  is  carried  up  into 
North  Carolina,  cotton  is  raised  in  Virginia  and 
figs  in  Maiyland — all  much  farther  north  than  on 
the  west  of  the  Alleghanies. 

We  shall  observe  with  interest  that  in  the  tide-water 
country  of  Georgia  ami  the  Carolinas,  rice  is  a  more  im- 
portant article  of  cultivation  than  in  Alabama,  Mississippi 
and  Texas.  There  is  a  geographical  reason  for  this.  The 
Atlantic  has  tides,  the  Gulf  of  Mexico  next  to  none.  Rice- 
flelds  require,  in  certain  stages  of  the  crop,  to  be  flooded. 
The  constant  renewal  of  the  water-supply  in  the  tidal 
creeks  and  rivers  of  the  seaboard  affords  facilities  and  con- 
veniences for  this  which  are  lacking  in  the  tideless  streams 
of  the  Gulf  States. 

The  Pacific  Slope. — The  agricultural  pursuits 
of  the  Pacific  Slope,  owing  to  its  j)hysical  peculi- 
arities, differ  from  those  of  the  Atlantic.  No  rice, 
cotton,  or  hemp  is  cultivated.  But  the  region  is 
unstiri^assed  for  its  wheat  and  fruit  crops ;  the 
olive,  the  vine  and  the  orange  yield  abundantly, 
while  stock-raising  and  wool-growing  are  jjrevail- 
ing  and  profitable  employments. 

Other  Industrial  Pursuits.  —  Considering 
now  the  various  other  industrial  pursuits  of  our 
people,  and  surveying  the  country  at  large,  we  find 
it  to  be  the  rule  that  Physical  Geography  has 
largely  determined  how  the  occupants  of  each  sec- 
tion shall  employ  themselves. 

Here  we  view  far-reaching  grass-covered  plains 
which  naturally  suggest  the  occupations  of  stock- 
raising,  dairying,  or  wool-growing.  Elsewhere  we 
traverse  forests  famed  for  lumber,  ship- timber  and 
naval  stores.  In  yet  another  region  we  observe 
that  attention  is  directed  to  the  great  lakes  or 
water-courses  for  fish  and  fowl  ;  or  to  the  interior 


of  the  earth  for  minerals  ;  or  to  commerce,  manu' 
facturing  and  navigation. 

All  these  occupations  are,  it  is  true,  adopted 
according  to  individual  fancy,  yet  still  they  are 
clearly  prompted  and  controlled  by  geographical 
circumstances. 

Industries  of  Newt  England  and  Gulf 
States  Contrasted.— A  very  striking  illustration 
of  the  law  of  geographical  distribution  of  labor  is 
obtained  when  we  contrast  the  leading  occups^ 
tions  of  such  widely  soijarated  sections  of  our 
country  as  the  Gulf  States  and  New  England. 

In  the  former  there  is  no  "wintry  weatJier." 
The  husbandman  may  labor  in  the  field  all  the 
year  long,  either  planting  or  reaping,  and  the  soil 
yields  abundantly. 

In  New  England,  on  the  other  hand,  thegi'ound 
is  covered  with  snow,  or  is  so  hard  frozen  that  it 
cannot  be  jiloughed  during  four  or  five  months  in 
the  year.  IIow  is  New  England  industry  to  ply 
its  liand  during  this  jjcriod  ?  It  cannot  till  ;  and 
it  will  not  do  to  stand  idle. 

The  ice-ponds  and  the  granite  quarries  then 
come  into  play.  The  stone  from  tlie  latter  is  dis- 
tributed along  the  Atlantic  sealjoard  for  building 
purposes  ;.  the  blocks  from  the  former  are  sent  to 
fill  the  ice-houses  in  London,  to  cool  the  sherbet 
of  the  nabob  of  India,  and  to  be  cried  in  the 
market-places  along  the  seaboard  of  intertropical 
countries. 

Again,  owing  to  the  geographical  conditions  of  New 
England,  her  forests  afford  her  hardy  sons  occupation  for 
"  lumbering  "  in  winter  and  ship-building  in  summer.  But 
after  supplying  these  branches  of  industry  with  laborers, 
New  England  has  others  that  would  still  be  standing  idle, 
were  it  not  for  the  factory  and  the  sea. 

Louisiana,  and  her  sister  Southern  States,  on 
the  other  hand,  want  laborers  for  their  harvests  of 
cotton,  corn,  sugar,  rice,  naval  stores,  hemp,  to- 
bacco, etc.  There  are,  therefore,  inducements 
peculiar  to  each  of  these  two  sections  which  allure 
the  people  of  one  to  this  branch  of  industry,  the 
people  of  the  other  to  that,  according  to  geo- 
graphical circiimstanccs.  In  one,  these  induce- 
ments lead  to  the  sea  and  the  factory  ;  in  the 
other  they  point  to  the  bosom  of  the  earth. 

Mining  and  Manufacturing. — If  coal  and 
the  useful  metals  are  found  in  any  region,  manu- 
facturing interests  will  sooner  or  later  be  devel- 
oped. It  is  in  no  small  degree  owing  to  her  vast 
deposits  of  coal  and  iron  that  Great  Britain  occu- 
jiies  her  extraordinary  position  as  a  manufacturing 
nation.  Pennsylvania  and  Ohio,  Maryland  and 
Michigan,  and  other  States  similarly  rich  in  the 
useful  minerals,  cither  are,  or  must  ultimately  be, 
actively  engaged  in  mining  and  metallurgy. 


GEOGRAPHICAL    DISTRIBUTION    OF    LABOR. 


125 


Fishing  and  Commkrce. — Again,  people  are 
maritime  in  their  liabits  from  jjliysical  reasons  ; 
partly  because  they  are  adjacent  to  tlie  sea ;  and 
partly  ■  Ijecause,  owiug  to  the  conditions  which 
surround  them,  the  bounties  of  tlie  sea  are  to 
them  more  enticing  than  tlie  bounties  of  the  land. 
Hence  you  find  that  tlie  seafaring  pojudations  of 
the  world  belong  chiefly  to  those  countries  where, 
either  from  the  poverty  of  the  soil,  the  severity  of 
the  climate,  or  the  high  price  of  food,  it  is  easier 
for  some  of  the  population  to  make  a  living  by 
braving  the  sea  than  hj  delving  on  shore. 

You  do  not  find  ships  at  sea  manned  by  sailors 
from  the  Mississippi  Valley  and  the  seacoast  of  the 
Southern  States,  where  lands  are  cheap,  climates 
mild,  and  where  the  soil  is  lavishly  kind  ;  but 
rather  from  New  England,  Great  Britain,  and  tlie 
countries  of  Northwestern  Europe,  where,  largely 
on  account  of  geographical  circumstances,  the 
laboring  man  finds  it  in  many  cases  easier  to  make 
a  living  at  sea  than  on  shore. 

Oriyin  of  Commerce. — It  only  remains  to  jioiiit 
out  how  commerce  between  nations  originates 
naturally  in  the  facts  of  jibysical  geography. 
Articles  required  for  food  and  shelter,  comfort  or 
luxury,  being  irregulai'ly  distributed  over  the 
globe,  it  becomes  necessary  that  human  industry 
should  be  partly  directed  to  the  exchanging  of  the 
I'.atural  and  artificial  products  of  one  region  for 
those  of  another.  As  will  be  seen  liy  an  inspec- 
tion of  map  on  pages  122  and  123,  the  routes  of 
commerce  are  determined  in  eall  cases  by  the  irreg- 
ular distribution  of  valuable  jiroducts. 


.?..  VonHunion. — Let  us  now  briefly  sum  up 
the  conclusions  of  our  science.  Physical  Geog- 
raphy teaches  us  to  see  order  and  law,  harmony 
and  design  in  every  part  of  the  terrestrial  ma- 
chinery. 

We  learn  from  it  that  the  very  position  of  the 
earth  at  a  certain  distance  from  the  sun  has  a  pur- 
pose— that  the  inclination  of  its  axis  has  an  im- 
jjortant  bearing  upon  climate  and  seasons  ;  that  not 
without  reason  do  the  mighty  waters  occupy  so 
large  a  proportion  of  its  surface  ;  that  they  yield 
of  their  abundance  to  refresh  the  dry  and  thirsty 
land  ;  that  the  wayward  winds  are  obedient  to 
law,  and  blow  for  definite  reasons  ;  nay,  that  even 
the  storm  and  hurricane  reveal  to  us  their  ordi- 
nances, although  we  may  not  discern  their  pur- 
poses. 

We  learn  that  mountains  are  not  simply  feat- 
ures of  the  landscape  intended  to  impress  us  with 
their  grandeur  and  beauty,  but  that  they  control 
tlie  rainfall  and  determine  where  the  vapor-laden 


winds  shall  discharge  their  burden  of  refreshment; 
and,  stranger  than  this.  Physical  Geography  in- 

structs  us  to  regard  the  very  deserts,  with  their 
arid  and  liurning  sands,  not  as  waste  areas,  but 
rather  as  invaluable  parts  of  the  vast  mechan- 
ism liy  wjiich  the  lands  of  the  earth  are  elotlied 
with  verdure,  and  tlie  labors  of  tlie  husbandman 
crowned  with  success. 

Borrowing  from  the  sister  sciences  of  chemistry, 
botany,  and  zoology.  Physical  Geography  discloses 
to  us  how  wondrously  the  inorganic  world  is 
adajited  to  the  support  of  ]ilant  and  animal  life, 
and  how  marvellously  these  interact  the  one  upon 
the  other.  It  tells  us  that  the  sturdy  oak  absorbs  its 
strength  from  the  unseen  air,  while  the  lichen  and 
the  daisy  spend  their  lives  in  elaborating  an  at- 
mosphere that  may  sup23ort,the  life  and  energy  of 
man  and  beast. 

In  a  word,  the  science  of  Physical  Geography 
unfolds  to  us  this  grand  view  of  our  iilanet,  that 
in  all  its  arrangements  there  is  proof  of  All-wise 
and  beneficent  design.  The  study  leads  to  a 
deeper  understanding  of  the  Psalmist's  words, 
"  The  earth  is  full  of  the  goodness  of  the  Lord ; 
so  is  the  great  and  wide  sea  also." 

TOPICAL    ANALYSIS. 

IV.    GEOGRAI'mCAL    DISTRIBUTION    OF    LABOR. 

1.  Distribution  Dependent  on  Physical  Geography. 

An  illustrative  example.  Diversified  industries  in 
middle  latilndes.  Grndual  increase  in  diversity 
as  middle  latitudes  are  apprnached.  Important 
industrial  pursuits  in  tliose  regions.  Consequent 
prosperity.  Characteristic  industries  of  polaraud 
equatorial  regions.     General  rule. 

2.  Industries  of  our  own  Country. 

.\gricultural  pursuits.  The  Mississippi  Valley.  Suc- 
cessive climatic  belts  and  their  characteristic 
products.  The  .\tlantic  Slope.  Cause  of  its 
broader  belts.  Advantages  for  rice  cultivation. 
The  Pacific  Slope,  agricultural  pursuits  of.  In- 
fluence of  physical  circumstances  on  other  in- 
dustries of  the  country. 

Industries  of  New  England  and  Gulf  States  con- 
trasted. Mining  and  manufacturuig  promoted 
by  mineral  wealth.  Circumstances  tending  to 
develop  the  industries  of  fishing  and  commerce. 
Origin  of  commerce. 

3.  Conclusion. 

Evidences  of  harmony  and  beneficent  design  in  the 
terrestrial  machinery. 

Test  Questions.— Name  three  or  four  canses,  aside  from  climate, 
which  may  affect  the  industries  of  a  people.  Name  some  advantages 
of  diversified  industries.  Do  you  thmk  there  is  any  intellectual  advan- 
tage, and  why  ?  Difference  between  savage  and  civilized  nations  as  to 
diversity  of  industries.  Is  the  diversity  liiccly  to  increase?  Why? 
How  does  increasing  diversity  affect  commerce  ?  In  the  United  Stales 
there  are  more  raih-oads  running  east  and  west  than  north  and  south  : 
cap  you  give  any  reasons  for  it  ? 


TOIMCAL   ANALYSIS    FOR    REVIEW. 


Relations  Between  Plants 
and  Animals.     .     .     . 


(  Life. 


Mutiml  Depemlence  of  Plants  , 
and  Animals. 


j  Organic  and  inorganic  nature. 

(  Flora  and  Fauna.  Pointsrelatingtothem  tobeconsidercjd 

What  animals  require  for  respiration. 

Effect  of  the  change  of  oxygen. 

Deleterious  pioduct,  how  disposed  of. ' 

Oxygen  prepaied  by  plants. 

Food  of  animals  supplied  by  plants. 

Mutual  cheeks. 

Influence  of  the  winds. 


Range  of  Plants  and  Ani- 
mals  


General  facts. 


Zones  of  Vegetation. 


Range  of  Food  Plants. 

Beverage  Plants. 
Spices  and  Narcotics. 
Plants  used  for  Clothing. 
Medicinal  Plants. 
Useful  Trees. 
Flora  of  the  Sea.     Algje. 


(  Range  dependent  on  climate. 
(  Modifications  by  climate.     Illustrations. 
f  How  defined. 

■:   Horizontal  zones.     Limits  and  characteristic  plants  of  each. 
I  Vertical  Zones.     Correspondence  to  horizontal. 

r  The  cereals. 

J   The  potato,  banana  and  mandioca. 
Bread-fruit  and  sugar  cane. 


Distribution  of  Animals. 


Why  dependent  on  climate. 
Zones  of  animal  life. 

r  Important  and  peculiar  forms  in  each. 
Zoological  regions,  -j   Australian   and  S.  American  regions, 

I       for  what  remarkable. 

Range  of  Draught  Animals.     Special  adaptation  of  some  to  locality. 
Ijimited  Range  of  some  Animals. 

r  Range,  by  what  mainly  determined. 
'   Life  of  tropical  waters.     Of  cool  waters. 
Range  of  the  seal;  reef-building  polyp. 


Fauna  of  the  Sea. 


Floral  Regions. 


(  Reasons  for  coincidence  with  zoological  regions. 
(  Plants  peculiar  to  each. 


Man. 


Range  of  Human  Habitation.     Vertical  range. 

Unity  of  Human  Family.     Diversity.     Causes  of  diversity. 

(  Divisions.     Extent. 
Caucasian  race.     .    -^  characteristics.     Superiority. 


J  Division  into  Races. 


Mongolian  race. 
Negro  race.     .     . 
Malay  race.     .     . 
American.  Indians. 


Extent.     Characteristics. 


Conditions  Favorable  to  Civilization.     Frigid  and  Torrid  Climates,  why  unfavorable. 

■,.     ,    r  a  Tiu     ■     1  ^  u      i  Extent  of  influence. 

Mans  Influence  on  Physical  Geography.     ,.^       .       .  ■  i   -i .      i  •     i 

I-  ■'  s    I-  J    j  Ways  in  which  it  has  been  exercised. 


Geographical  Distribution 
of  Labor 


Dependent  on  Physical  Geography.     Diversified  industries  in  middle  latitudes. 

C  r  The  Mississippi  Valley. 

Agriculture.    J   The  Atlantic  Slope. 
1   The  Pacific  Slope. 
Industries  of  our  own  country.  -{   Influence  of  circumstances  on  other  industries. 

Industries  of  New  England  and  Gulf  States  contrasted 
Mining  and  manufacturing. 
[  Fishing.     Commerce.     Origin  of. 
[Conclusion.     Evidences  of  harmony  and  design. 


PRONOUNCING  VOCABULARY. 


Explanation.— In  this  VocabiiI»ry  thu  best  and  most  recent  uuthoriticH  have  been  connilted  for  both  spelling  and  pronunciation.  *  or  ay,  C, 
I,  Ti,  0,  arc  to  be  pronounced  us  in  bate,  niele,  bite,  note,  tube ;  a,  C,  I,  ft,  u,  an  in  bat,  bet,  bil,  not.  but.  The  8oiin(l  4if  a  in  far  in  indicated  by  (i/i  ; 
a  hi  fall,  l)y  aw ;  o  in  do,  by  oo  ;  g  in  {nt^  by  (jh.     U  reprei-ents  the  souiui  of  eu  in  Frencii,  wliicli  lesenibleH  the  .sound  of  e  in  her. 

The  nasal  sound  occurrintr  in  :^nnie  French  words  i8  indicated  by  N,  as  Toulon  (too-loN) ;  this  nasal  sound  in  Komewhat  lilic  that  of  ug  Mntnded 
tlirough  the  nose.  Letters  inclosed  by  (,  )  indicate  pronunciation.  In  some  cases  two  aeceuls  wdl  be  found  in  one  word.  The  principal  accent  \>^ 
represented  by  ',  the  gecondary  by  ^  . 


Abyssinia  (ab-is-sin'ia). 

Aconcagua  (ah-kon-kah'gwah). 

Aegean  (G-je'an). 

Afghanistan  (af-ghau-is-tabn'). 

Alas'Ua. 

Aleutian  (al-oo'she-an). 

Altai  (iihl-tl'). 

Am'a-zon. 

Amboyna  (am-boi'nah). 

An'des  (an'dGz). 

Antigua  (an-tG'gwah). 

A-pa'che. 

Ap-pa-la'chi-an. 

Ap'en-nines. 

Ar'ab. 

Ar'a-rat. 

A-rau-ca'ni-an. 

Archipelago  {ark-I-pel'a-go). 

Argentine  (ar'jen-ten). 

Ari-zo'na, 

Artois  (abr-twah'). 

Az'ov  (az'of). 

Az-ores'. 


Baikal  (bT'kalil). 

Balkan  (buhl-kuhn'). 

Baltic  (bawl'tic). 

Bar-ba'docs  {-dOz). 

Bedouin  (bed'tio-Sn). 

Behring  (bS'ring). 

Bel-oo-chis-tan'. 

Bencoolen  (ben-koo'len). 

Bengal  {ben-gawl'j. 

Bep'ho. 

Ber-nard'. 

Bhooj  (booj). 

Blanco  (blang'ko). 

Bogota  (l)o-go-tah'). 

Bo-liv'i-a. 

Bor'ne-o. 

Boschen  (bo-shen). 

Brah-ma-poo'tra. 

Brazil  (brah-zil'). 

Bund  (boond). 

Bur'mah. 


Cairo  (ki'ro  ;  in  U.  S.  ka'ro). 

Callao  (kal-lah'O,  w  kal-yah'o). 

Campagna  (cam-pan'yah). 

Can'a-da. 

Cafion  (can-yOn'). 

Caracas  (cah-rah'cas). 

Carib-be'an. 

Cassiquiare  (cah-sc-kG-ah'rai. 

Cau'ca-sus. 

Celebes  (sel'e-bez). 

Ceylon  (sG'lon.  or  se-lon'). 

Chary bdis  (ka-rib'dis). 

Cherrapungee  (cher-ah-poou-je')- 

Chili  (chil'le). 

Cir-cSs'sian. 

Co'mo. 

Comorin  (kora'o-rin). 

Coseguina  (ko-sa-ghe'nah). 

Cotopaxi  (co-to-pax'e). 

Cumana  (ku-mah-nah'). 

Dcc'can. 
Dnieper  (nS'perV 
Dniester  (nGs'ter). 
Dwina  (dwG'nah), 


Ecuador  (ek-wa-dOr'). 
Esquimaux  (es'ke-mo). 
Estacadn  (es-tah-kah'do). 
Etesian  (e-tG'zhan). 
Eu-phra'tes  (yoo-fra'tGs). 

Fiord  (fe-ord'). 

Gal-a-pa'gos  (gal-a-pah'gos). 

Ganges  (gan'jezj. 

Garonne  (gah-ron'j. 

Geant  (zha'oNg). 

Ge-nC'va. 

Geysers  (ghl'zers). 

Ghauts  (gawts). 

Gobi  (gO'»)G). 

Crenelle  (greh-nell'). 

Grim'sel. 

Guadaloupe  (gwah'da-loop). 

Guatemala  {gwah-te-mab'la). 

Guayaquil  (gwT-ah-kCl'). 

Guiana  (ghe-ahn'a). 

Guinea  (ghin'e). 

Ham'mer-fest. 

Han'lG. 

Hawaii  (hah-\\ah'e). 

Hayti  (ha'te). 

Her-cu-la'ne-um. 

Himalaya  (hini-a-hl'ya,  or  him-ah'- 

la-ya). 
Hoogly  (hoog'lee(. 

n)i  Gamin  (ee'bc  gah'rain). 
Illimani  (el-ye-mah'ne). 
Indies  (in'diz). 

Jamaica  (ja-ma'kah). 
Jan  Mayen  {yahn-ml'en). 
Java  (jah'vah). 
Jax-ar'tes  (tez). 
Jorullo  (ho-rooryo). 

Kamtchatka  (kam-chat'ka). 

Kar-a-ko'rum. 

Keni'a. 

Ke'o-kuk. 

Kergurlen  (kerg'e-len). 

Khamsin  (seen). 

Khar-toom'. 

Khasia  (kas'se-ah). 

Khingan  (kin-gan')- 

Khiva  ikG'vahK 

Kilauea  (koi--l(3w'a-ah). 

Kilima-Njaro  (kil-e-mahn-jar-o'). 

Kirghiz  (kir-ghez')- 

Klint-chevs-kaia  (kahe-ah). 

Kuen  Lun  (kwen  loon). 

Kurile  {koo-rGl,  or  koo'ril). 

Ku'ro  Si'wo  (sG'wo). 

Labrador'. 
La'-do-ga. 

La  Plata  (lah  plah'tah). 
Lar'sa. 

Lauricocha  (low-re-co'chah). 
Le'chaud  (la-sho'). 
Lipari  (lip'a-ro). 

Llano    Estacado     (lyah'no  es-tah- 
kah'do). 


Llanos  (lyah'nOa). 
Lo-fO'den. 


Macassar  (ma-kas'sari. 

Mad-agas'car. 

Magellan    (ma-jel'lan,    or    mnj-el- 

lan'). 
Maggiore  (mahd-jo'ra} 
Malacca  (ma-lak'ka). 
Ma- lay'. 

Maravaca  (mah-rah-vah'kah). 
Marquesas  (mar-ka'zas). 
Mar-a-cay'bo  (-kl-bo). 
Martinique  (mar-te-nGk'). 
Mauritius  (niaw-rish'e-iis). 
Maz^al  Ian'. 
Mekong  (ma-kong'). 
Medusai  (me-du'sa). 
Mer  de  Glace  (mair  de  glass). 
Messina  (mes-sG'nah). 
Mille-po-ra. 
Mon'derf. 
Mon-gO'li-an. 
Mont  Blanc  (moN  bloN'). 
Mozambique  (mo-zam-bGk'). 

Nevada  (ne-vah'dah). 

New-found'land  {or  nu'fund-land). 

New  Zea'land. 

Ni-ag'a-ra. 

Ni'ger  (nl'jer). 

Nisyros  (nis'e-ros). 

NyaTiza  (ni-an'zah). 

Nyassa  (ne-as'sah). 


0-des'sa. 

Okhotsk  (o-kotsk'). 

One'ga. 

Oppido  (op'pe-do). 

Orizaba  (o-re-zah'bah). 

0-ri-no'co. 

Ox'us. 


Pamir  (pah-niGr'). 

Pamperos  (pam-pa'ros). 

Pan-a-ma'  i-mali). 

Pa-pan-da-yang'. 

Parime  (pah-re'ma). 

Pas'lo. 

Pa-ta-go'ni-a. 

Peking'. 

Periades  (pay-re-ad). 

Peru  (peroo'). 

Plata  (plah'tah). 

Plateau  ipla-to'). 

Polynesia  (pol^e-nee'she-a). 

Pompeii  (pom-pa'yG). 

Porto  Rico  (port'o  rG'ko). 

Puna  (poo-nah'). 

Puy  de  Dome  ipwee-deh-dom'). 

Pyr'-e-nees. 

Quito  (kG'to). 


Riiinier.(ra'neer). 
Re'gia. 
Rhine  (rln). 
Rhone  (ron). 


Riobamba  Oe-o-bam'bahj. 
Rio  d('  la  Plata  (re'o  da  luJi  plah'- 
tah). 
Roque  (rOk). 


Sahara  (sah-hah'rah). 
Salzwerk  (.«alts'werk). 
Santorini  (san-lo  ree'nee). 
St.  Etienne  (sant  fi-tc-Gn'). 
St.  Gothard  (go-tar'). 
Sas-katch'e-wan. 
Sen-c-gam'bia  (bc-a). 
Sierra  Madre  (se-er'rah  mah'dra). 
Sierra  Nevada  (se-er'rah  ne-vah'- 
dah). 
Simplon  (sam-ploNg). 
Sioux  (soo). 
Si-roc'co. 

Skaptar  JOkul  (skap'lar  yu-kool'). 
Sol-fa-ta'ra  (tah'rah). 
Spitz-berg'en. 
Stanovoi  {stahn-no-voi'). 
Steppes  (steps). 
Strom'bo-li. 

Suleiman  (soola-mahn'). 
Sumbawa  (soom-baw'wah). 
Sumatra  (soo-mah'tra). 
Sun'da. 
Sy'ri-a. 


Tahiti  (tah-hg'te). 

Tal-efre. 

Tanganyika  (tahn-gahn-yG'kab). 

TanjitT  (tahn-jer'). 

Tliian  Shan  (te-ahn'shahnj. 

Thibet  (lib'et  w  tib-et'). 

Ti'gris. 

Titicaca  iti-ti-kah'kahi. 

To'kio  (ke-o). 

Torricelli  (tor-re-chel'Ie). 

Tor-to'la. 

Tristan    d'Acunha     (tris  tan    fla- 

koon'yah). 
Tsetse  (zeet-zce). 
Tsi-en-tsang'. 

Tungnragua  (toong-goo-rah'gwah). 
Ty-phoon'. 


Upemavik  (oo'per  nah'^vik). 

U'ral  or  Ou'ral. 

U'ra-nus. 

Unimtsi  (oo-roomt'see). 

Valdai  (vaI'dT). 
Venezuela  (ven  e-zwG'la). 
Vindhya  (vind'yah). 

Wen'er. 

Yablonoi  (yah-blo  not'). 

Yakutsk  (yah-koot.«k'). 
Yang-tse-Kiang      (yahng^tse     Kc- 

ang'). 
Yo-sem'i-te- 
Yu'kon. 

Za'gros. . 

Zambezi  (zam-ba'ze). 


128 


MEAN    TEMPERATURE    Ar}D    RAINFALL. 


TABLES   OP   MEAN   TEMPERATURE   AND   RAINFALL. 


NAMES   OP   PLACES. 


UNITED  STATES. 

Albany,  N.  Y 

Amherst,  Mass 

Astoria.  Or, 

Augusta,  Ga 

Austin,  Texas 

Baltimore,  Md 

Baton  Rouge,  La 

Boston,  Mass 

Brownsville.  Tex 

Buffalo,  N.  Y 

Cedar  Keys,  Fla. 

Cincinnati.  O 

Chapel  Hill,  N.  C 

Cliarleslon,  S.  C  

Chicago.  Ill 

Cleveland,  O 

Columbia.  S.  C.  

Concord,  N.  II 

Denver,  Co! 

Des  Moines.  Iowa 

Detroit,  Mich 

Dubuque,  Iowa 

Eastport,  Me. 

?''ort  Benton,  Mont 

Fort  Dallas,  Fla 

Fort  Kearney,  Neb  

Fort  Leavenworth,  Kan.. 

Fortress  Monroe.  Va 

Ft.  Snelling.  St.  PauI.Min . 
Fort  Washita.  Ind.  Ter.. 

Fort  Yuma.  Cal 

Galveston,  Tex 

Uuntsville,  Ala 

Key  West,  Fla 

Little  Rock,  Ark    

Los  Angeles,  Cal 

Louisville,  Ky 

Memphis.  Tenn. 

Milwaukee,  Wi^ 

Mobile.  Ala 

Nantucket,  Mass     

Nashville.  Tenn 

Natcliez,  Miss 

New  Haven,  Conn 

New  Orleans.  La 

New  York,  N.  Y 

Pembina,  Duk 

Penaacola,  Fla " 

Philadelphia,  Pa 

Point  Barrow,  Alaska 

Portland.  Me 

Providence,  R.  I .• , 

Richmond,  Va 

Rochester.  N.  Y 

Sacramento.  Cal .   . . 

St.  Louis,  Mo , , 

Salt  Lake  City,  Utah 

San  Diego,  Cal 

San  Francif  CO,  Cal 

Santa  Fe,  N.  M... 

Savannah,  Ga 

Sitka,  Alaska 

Washington,  D.  C 

West  Point.  N.  Y 


NORTH    AMERICA. 


Assjnlboine.  Manitoba 

Guatemala,  Cent.  Am 

Havana,  Cuba 

M.itamoras.  Mexico 

Mexico,  Mexico 

Montreal,  Canada ' . 

St.  .Inhns,  NcwFoundland  .. 

St.  Thuni.is.  West  Indies  ...  _. 

UpLTiuivik,  Greenland 1  73  40 


North 

1 
Jnny. 

Lat. 

zero  — 

42»3!)' 

24.3 

48  23 

2.3.7 

46  11 

43 

33  88 

46.7 

30  16 

46.4 

39  17 

.30.9 

30  26 

53.5 

42  22 

27.8 

25  M 

60.4 

42  63 

89  r 

55.6 

39  6 

30 

35  54 

41.5 

32  46 

48.1 

41  53 

23.6 

41  30 

33  57 

43  12 

21.2 

39  44 

32 

41  35 

27.4 

42  20 

27 

42  30 

19.8 

44  54 

22.4 

47  50 

16.5 

2i  55 

66.4 

40  38 

21.1 

39  81 

28 

37 

36.5 

44  53 

13.7 

34  14 

42.9 

32  44 

56.4 

29  18 

48.1 

34  43 

42 

24  34 

69.5 

34  42 

40 

.34  3 

52.8 

38  3 

35  8 

a?  8 

41.7 

43  3 

85.2 

30  41 

57.6 

41  17 

34.9 

36  9 

38.2 

31  34 

52.3 

41  18 

29  57 

55.3 

40  42 

30.2 

49 

30  24 

53.6 

39  67 

32.1 

71  21 

-18.5 

43  39 

22.8 

41  50 

27.5 

37  32 

3.3.7 

438 

26.9 

38  34 

45.3 

38  37 

31,4 

40  46 

27.1 

32  42 

51.9 

37  48 

49.  B 

35  41 

.31.4 

32  5 

54.4 

57  3 

32 

38  53 

28.3 

41  24 

28.3 

50 

-2.9 

14  40 

65 

23  9 

71.4 

25  62 

60.4 

19  85 

52.5 

45  31 

15 

47  37 

23.4 

18  21 

80.S 

72  40 

•  12.3 

Annu'I 

July. 

Year. 

rainfall 

in 
inches. 

72.1 

48.2 

40..52 

71 

46.7 

43.90 

61.6 

53.2 

86.35 

81.9 

64 

24.20 

80.7 

66.7 

30..50 

75.2 

5:3.1 

40.81 

81.8 

68.1 

60.16 

71.6 

48.9 

39  40 

84.2 

73.7 

37 

46.1 

33.84 

81.3 

70.5 

45.77 

74.5 

53.8 

44.87 

78.2 

.59.7 

42.71 

80.1 

65.9 

41.92 

70.8 

46.7 

33 

48.9 

37.61 

57.1 

47.17 

67.1 

44.5 

40.99 

78 

48 

16 

76.5 

49.7 

8;1.94 

69. 7 

47.2 

30.  U5 

75.2 

49.4 

a3.47 

62,3 

43 

40.09 

73.6 

48.2 

18.50 

82.1 

74.7 

59.01 

73.5 

47.7 

25.25 

76.7 

52.8 

31.74 

78.2 

59.9 

47.04 

r3.4 

44.6 

25.88 

80.7 

62.2 

.38.04 

92.3 

73.0 

3.46 

83 

69.4 

42 

76.4 

59.1 

54,88 

82.5 

76.4 

36.23 

NO 

62.3 

47 

75 

62 

13 

74.6 

549 

48.12 

79.9 

60.8 

45.46 

69.8 

46.4 

30.40 

8.3.7 

70.3 

64.42  - 

71 

50.4 

41.10 

79.5 

685 

52.02 

81.3 

67.1 

53.55 

50.S 

44  43 

88.9 

69  9 

51.05 

74  8 

51.7 

44.59 

74.4 

15 

82.3 

68.7 

59.27 

74.7 

52.7 

35.55 

36.1 

7.1 

6S.2 

45.2 

43.63 

70.6 

47.9 

41.38 

77.6 

56  2 

38.29 

69.9 

47 

32.56 

739 

59.9 

19..59 

78.2 

54.5 

42  48 

81.5 

28,85 

72  7 

02 

9.16 

.57.9 

54.9 

2.3.50 

T2.6 

50.6 

17 

81.4 

67.4 

48.32 

55.5 

43.2 

83  — 

76.7 

56.1 

41.05 

73.7 

50.7 

47.65 

69.6 

35.3 

68.9 

67.8 

55 

81.4 

77.1 

40 

84.2 

73.6 

37 

65.3 

60.7 

73.2 

44.6 

42 

66 

38.3 

63 

82.7 

82.3 

35 

38.5 

12 

NAMES  OP  PLACES. 


SOUTH  AMERICA. 

Bojota.U.S.  of  Colombia 

Lima,  Peru  (south  lat.) 

Quito.  Ecuador  (south  lat.> 

liio .Janeiro,  Brazil  (south  lat.). 
Valparaiso,  Chili  (south  lat.)... 


Athens.  Greece. 
Bel<?rade,  Turkey.  ..... 

Bergen,  Nor%vay 

Berlin,  Germany 

Bordeaux,  France    

Bremen.  Ciermany 

Brussels,  Be]«iuiTi 

Christiania,  Nonvay 

Constantinople.  Turkey. 

Dublin,  Ireland 

Edinburf'h,  Scotland 

Elcuterinburg,  Russia 

Florence,  Italy 

Ilammerfest.  Norway 

Lisbon,  Pottufjal 

London.  England 

Lyons.  France 

Madrid.  Spain 

Milan,  Italy 

Moscow,  Russia 

Naples,  Italy 

Odessa.  Russia 

Paris.  France    

Reykjavik.  Iceland 

St.  Petersbur<r,  Russia. . . 
Vienna,  Austria 


North 
Lat. 


ASLA. 

Aden,  .\rabia 

Amboyna,  Molucca  Ids 

Bagdad.  Asiatic  Turkey 

Bankok,  Siam 

Barnaul,  Siberia 

Batavia 

Bombay.  Ind 

Calcutta,  India 

Canton,  China  

Irkutsk,  Siberia  

Jenisalem.  Syria 

Manila,  Philippine  Ids 

Nagasaki.  Japan. 

Peking,  China 

Petropaulovski,  Kamtchatka 

Singapore 

TiHTs 

Tobolsk,  Siberia 

Yakutsk,  Siberia 


Algiers,  ,\lgeria 

Cairo.  Egypt 

Cape  Town,  Cape  Colony,  (s.lat.) 

Christiansburg.  Guinea . 

Funchal,  Madeira 


ISLANDS  op  THE  PACIFIC 


Adelaide.  Australia  (s.lat.V 
Auckland.  New  Zealand, (s. 
llonolulu.  Sandwich  Ids. . . 
Sydney,  Austialia  (s.Jat.).. 


lat.t 


4°36' 
12  3 

0  14 
22  54 
33  2 


Archangel,  Russia 64 

Astrakan,  Russia 46 

37 
44 
60 
58 
44 
53 
50 
69 
41 
53 
55 
56 
43 
70 

as 

50 
45 
40 
45 
65 
40 
46 
48 
64 
59 
48 


36  47 
30  2 
a3  56 
52  4 
38  38 


34  55 
36  50 
21  18 
33  51 


Jan'y. 
(Below 


57 

78.1 

58.8 

79.6 

66 


22.5 
19.9 
45.5 
33.3 
35 
28.1 
42.4 
29.0 
36 

21.31 
40.4 
40.4 
37.4 
2.3 
40.8 
22.5 
48.6 
37.4 
36.3 
447 
333 
11.9 
46.8 
26.1 
35.4 
30 
15.5 
28.9 


72.6 
80  5 
48.6 
76.7 
-14 
78.7 
73.3 
71.7 
52  5 
-6.5 
46.7 
77.1 
42.3 
25.8 
20.3 
78.4 
324 
-2.9 
-41.3 


59.1 
663 
67.6 
81.1 
63.5 


84.4 
67.9 
71.7 
71.7 


luly. 

Year. 

56.2 

57.7 

68.5 

73.3 

.59.1 

IKl.l 

706 

75.2 

57.3 

60.6 

.52.2 

35.5 

77.9 

49.2 

79.5 

62.4 

76.6 

54.2 

60.4 

46.8 

6H.8 

48.2 

69.1 

55.1 

64.6 

48.1 

64.8 

50.3 

61 

41.1 

74.1 

57.6 

.58.2 

48.4 

58.5 

47.1 

Si.H 

38,2 

76.3 

57 

63  2 

35.5 

69  8 

59.5 

64.1 

50.8 

70  6 

52.4 

76  3 

68 

74  5 

546 

67.8 

40.4 

75,4 

59.9 

71,5 

49.2 

fi.5.6 

61.3 

.56  2 

39.4 

62.5 

38.8 

69.5 

50.2 

83.4 

802 

77 

79.1 

93.2 

73.6 

82 

81.1 

67.5 

32.3 

78 

78.8 

80.7 

79.8 

&I.2 

81.1 

K\ 

69.9 

64.9 

30.7 

76,4 

63  6 

80,3 

79.5 

79.3 

61 

7S.9 

54.6 

:m] 

37 

82.  > 

80.7 

75  6 

55 

63.4 

33 

63.8 

12.4 

80.4 

69.1 

85.6 

71.3 

,54.4 

60.7 

77.1 

80.4 

?2.5 

67.6 

54.2 

68.4 

49 

58.6 

78.9 

75.4 

49.8 

61.3 

Annu'i 
rainfall 


inches. 


53 


6 

10 

86 

88  • 

23 

26 

24 

29 

21 

29 

29 

19 

15 

35 

27 
19 
31 
18 
38 

31 

83 
31 
18 
18 


12 

149 
84 
68 

i  78 


24 


0 
19 
144 
28 


INDEX 


^HTRsmiA,  plateau  of,  3f>. 

Africa,  animals  peculiar  to,  100, 
113;  dusert  of,  aC) ;  drainiige  of, 
52;  lalcL'8  of,  50;  mountain- 
ranges  of,  36,  37  ;  plains  of,  37  ; 
plants  peculiar  to,  115;  plateau 
of,  3r  ;  raius  of,  92  ;  winds  (.f, 
89,  92. 

Air,  carbonic  acid  of,  69  ;  circula- 
tion of,  76,  77  ;  composition  of, 
69  ;  density  of,  70 ;  effect  of 
pressure  of  on  boiling-point  of 
water,  70;  effect  of  pressure 
of  on  man,  113;  height  of,  10; 
moisture  of.  85-96 ;  movement 
of,  75,  7fi;  weight  of,  69,70. 

Aleutian  Current,  65. 

Alps,  35  ;  aspects  of  the,  33  ;  ava- 
lanches of,  94 ;  average  height 
of,  33  ;  glaciers  of,  97 ;  passes 
of  29;  snowfall  on,  94;  why  so 
famed,  33. 

Altai  Mountiiins,  35.  36. 

Amazon,  47 ;  basin  of  the,  32  :  bore 
of,  60  ;  tides  in,  60  ;  water  dis- 
charged by,  51. 

America,  North,  animals  peculiar 
to,  109;  drainage  or,  51 ;  Indians 
of,  118;  lakes  of,  49;  mountain- 
ranges  of,  30,  31  ;  plains  of.  31  ; 
plants  peculiar  to,  115;  plateaus 
or,  31;  watershed  of,  51;  winds 
of,  80,  89,  92. 

America,  South,  animals  peculiar 
to,  112,  113;  curious  facts  about 
river  basins  of,  32;  drainiige  of, 
51  ;  lakes  of»  50 ;  mountain- 
ranges  of,  31  ;  plains  of,  32 ; 
plants  peculiar  to,  115;  plateaus 
of,  32;  rainfall  of,  89;  watershed 
of,  51 ;  winds  of,  80,  89. 

Andes,  28,  35,  4S;  elevation  of,  32; 
extent  of,  31;  influence  of  on 
rainfall,  89  ;  peaks  of,  32  ;  vege- 
tation of,  106. 

Anemometer,  75. 

Animals,  distribution  of,  108;  divi- 
sion of  the  earth's  surface  into 
regions  of,  109;  food  for  sup- 
plied by  plants,  101  ;  limited 
range  of  some,  113;  modifica- 
tions of  by  climate,  103;  of  the 
eea,  114;  oxygen  required  by, 
101;  range  of  draught,  113; 
zones  of,  108. 

Antarctic  Ocean,  currents  of,  64,  65. 

Apennines.  33. 

Appalachian  Mountains,  31. 

Arabia,  plateau  of,  36. 

Arctic  Ocean,  34,  36,  49,  51;  cur- 
rents of,  64,  65. 

Arkansas,  hot  springs  of,  14. 

Armimia,  plateau  of,  36. 

Artesian  wells,  action  of,  45  ;  tem- 
perature of,  13;  why  so  called,  45. 

Asia,  animals  peculiar  to,  109  ; 
drainage  of,  51  ;  hikes  of,  50  ; 
monsoons  of,  92 ;  mountain- 
ranges  of,  34,  35,  36;  plains  of, 
36;  plants  peculiar  to,  115;  pla- 
teau of,  34,  36;  winds  of,  80,  89 

A^ia  Minor,  plateau  of.  36. 

Atlantic  Ocean,  bed  of.  54  ;  cur- 
rents of,  61;  depth  and  form  of, 
54;  fogs  of,  87;  influence  of  on 
climate  of  Western  Europe,  74  ; 
Sargasso  sea  of,  67  ;  storms  of, 
85;  telegraphic  plateau  of.  54  ; 
tidiil-wavu  in.  58. 

Atlantic  Slope,  industries  of.  124. 

Atlas  Mountains.  37. 

Afmnsphere,  composition   of,  69; 


electricity  of,  98  ;  weight  of, 
119. 

Atolls,  origin  of,  40,  41. 

Aurora  Borealis,  eause  of,  98;  dis- 
tribution of,  99;  nature  of,  99; 
relation  of  to  magnetic  storms. 
12;  where  most  frequent,  99. 

Australia,  animals  peculiar  to,  109; 
barrier  reef  of,  38.  66;  drainage 
of,  52 ;  lowland  of,  37;  mtuint- 
ains  of.  37;  natives  of,  117; 
plants  peculiar  to,  115;  winds 
of.  80. 

Australian  Alps,  37  ;  Current,  65. 

Avalanches,  94. 

Balkans,  32,  34. 

Baltic  Sea,  34,  66. 
Barometer,  discovery  of,  69. 
Bhooj,  destruction  of,  22. 
Black  Sea.  32,  ^. 
Bogota,  rains  of,  92. 
Bolivia,  plateau  of,  32. 
Bores,  most  remarkable,  60. 
Brazil,  41;  Current,  61. 
Buda-Pesth,  artesian  well  at.  13. 

Calm  Belt,  movement  of,  92. 

Calms  of  Cancer.  78 ;  Capricorn, 
78 ;  Equator,  78. 

Camel,  range  of,  113. 

Cameroons  Mountains,  37- 

Cafions,  as  evidences  of  age  of 
earth,  29  ;  how  produced,  29. 

Caracas,  destruction  of,  22. 

Carpathian  Mountains,  33. 

Cascade  Mountains,  influence  of  on 
rainfall,  89. 

Caspian  Sea.  32.  33,  34.  49. 

Caucasian  Race,  characteristics  of, 
117;  extent  of,  116;  origin  of 
name  of,  116. 

Caucasus  Mountains,  33. 

Cherrapunjeo,  rainfall  of,  93. 

Chili,  23,  32;  rains  of,  89. 

China,  36.  48,  65;  plains  of,  28. 

Circulation,  of  the  air,  76,  77;  of 
the  sea,  65,  66:  of  water,  44. 

Civilization,  conditions  favorable 
to,  118-  early,  118. 

Climate,  causes  which  modify.  70; 
effect  or  distance  from  the  Equa- 
tor, 70,  71;  effect  of  distance 
from  the  sea.  71 ;  effect  of  height 
above  the  sea-level,  74;  effect  of 
winds  and  ocean  currents,  74; 
inland,  74;  insular,  71  ;  main 
elements  of,  70;  plants  and  an- 
imals modified  by,  102,  103. 

Climatic  contrasts,  71. 

('loud-ring,  movement  of,  92. 

Clouds,  classification  of,  87;  height 
of,  88;  offices  of,  88;  origin  of. 
87;  velocity  of.  88;  why  they  do 
not  fall,  88. 

Colorado,  cafion  of,  29. 

Condensation.  86;  exertsa  warming 
influence,  44. 

Con-tant  precipitation,  region  of, 
92. 

Continents,  26:  axes  of,  30;  general 
eliefof.  30, 

Copernicus,  theory  of  concerning 
the  earth,  6. 

Coral,  distribution  of.  41;  groves 
and  seas,  40;  islands,  formation 
of,  39,  40:  polyp,  description 
and  work  of.  39,  40:  reefs,  39, 
40,  41,  66. 

Crater,  defined,  15. 

Currents  of  the  Sea,  61;  causes  of. 
65,66,  67;  classification  of,  61; 


courseB  of,  how  modified,  61; 
influence  of  on  climate,  74;  of- 
fices of,  67. 
Cyclones,  81;  illustrations  of,  82. 

Di;ai)Sea,  36,  49. 

Deccan,  plateau  of,  36. 

Deltas,  productiveness  of,  27. 

Deserts,  importance  of,  28;  influ. 
ence  of  on  rainfall,  89;  of  Africa, 
37.  93;  of  Asia,  35,  36.  93. 

Dew,  formation  of,  86. 

Dew-point,  86. 

Drainage,ad  vantages  of,50;  changes 
wrought  by  artificial,  120;  how 
effected,  50 ;  of  Africa,  52  ;  of 
Asia,  52  ;  of  Australia,  52  ;  of 
Europe,  51;  of  North  America, 
51;  of  South  America,  51. 

Dry  and  rainy  seasons,  89  ;'  a  cause 
of.  92,  93. 

Earth,  adaptation  of  for  human 
habitation,  9;  a^  a  planet,  6; 
ancient  theory  of,  6;  effect  of 
inclination  of,  9;  effect  of  rota- 
tion of  on  oceanic  currents,  61; 
internal  heat  of,  13;  interior  of, 
14;  magnetism  of,  10,  12;  mag- 
netic poles  of,  12;  motions  of,  8; 
orbit  of,  9;  relative  size  and  im- 
portance of,  8;  seasons  of,  9. 

Earthquakes,  causes  of, 22;  changes 
produced  by,  22;  description  of, 
21;  distribution  of,  22;  effect  of 
upon  the  sea,  21;  relation  of  to 
volcanoes,  22. 

Egypt  and  the  Nile,  52,  92,  93. 

Elburz  Mountains,  35,  36. 

Electricity,  atmospheric,  98;  mani- 
festations of,  98. 

Equator.  70,  71,  74. 

Equatorial  Current,  61,  65;  cause 
of,  67. 

Etesian  winds,  80. 

Europe,  contrasted  with  North 
America,  32;  animals  peculiar 
to,  109;  axis  of,  32;  drainage  of, 
51 ;  lakes  of,  49;  mountain  ranges 
of,  32,  33;  peninsulas  of.  33; 
plains  of,  33,  34;  plants  peculiar 
to,  115;  rivers  of,  51. 

Evaporation,  effect  of  on  rain- 
fall, 66;  effect  of  on  sea- 
water,  66;  exerts  a  cooling  in- 
fluence, 44;  how  increased,  86. 

Fauna  of  the  Sea,  114. 

Fiords.  34. 

Flora  and  fauna,  101. 

Flora  of  the  sea,  108. 

Floral  regions  of  the  earth,  114. 

Fog,  formation  of,  86:  where  most 

abundant,  87. 
Food  plants,  range  of.  106,  107. 
Fundy,  Bay  of,  tides  in,  58. 

Galileo,  discovery  by,  69. 

Garonne,  bore  of  the.  60. 

Geology,  illustrating  climatic  in- 
fluence upon  life  of  the  earth, 
102. 

Geysers  defined.  14:  location  of, 
14;  of  the  Yellowstone  Park, 
14;  temperature  of,  14. 

Ghauts  Mountains.  36:  effect  of  on 
rainfall,  89- 

Glaciers,  aspect  of,  94,  95;  as  river 
sources,  97;  distribution  of,  97; 
formation  of,  94:  moraines  of, 
96;  motion  of.  95:  of  Alps.  97; 
of  Greenland,  97;  of  the  Hiina- 


layns,  97;  of  the  United  Statc^ 
97;  size  of,  97 ;  transportinu 
power  of,  96;  work  of.  9f. 

Gohi,  Deseit  of,  35,  36.  K!). 

(iraham  Island,  formation  of,  :j8. 

Grand  Banks,  fogs  of,  64,  87;  how 
formed,  97. 

Great  Britain,  38  ;  dimatc  of,  74; 
rainfall  of,  93:  tides  of,  60. 

(Jrechm  IVniiisula,  :M. 

Greenland,  sub.>.idence  of,  29. 

Grenelle,  artesian  well  at.  13. 

Gulf  of  Mexico,  sediment  carried 
into,  47;  tides  in,  58. 

Gulf  Stream,  67;  color  of.  53.  64; 
dimensions  of,  64;  influence  of 
on  climate,  74;  offices  of,  64; 
temperature  ol,  64. 

Hail,  formation  of,  94. 

Halos,  99. 

Hecla.  lava  from,  16. 

Herculaneum,  17. 

Himalaya  ^lountains,  27:  aspects 
of,  34;  elevation  and  length  of. 
34;  glaciers  of,  97;  influence  of 
on  rainfall,  89;  passes  of.  35. 

Hindoo  Koosh  Mountains.  34.  36. 

Holland,  reclamation  of  land  in, 
120. 

Hooghly,  bore  of  the,  tiO. 

Horizon,  defined.  53. 

Human  family,  conditions  favor- 
able to  civilization  of,  118;  di- 
versifled  iudustries  of  in  middle 
latitudes,  121;  diversity  of,  116; 
division  of  into  races,  116;  hal> 
itation  of.  116:  unity  of,  116. 

Humboldt  Current,  65. 

Iberian  Peninsula,  33. 

Icebergs,  distribution  of,  97;  origin 
of,  97. 

Ice,  effect  of  pressure  on  meltir  p 
point  of.  96:  law  by  which  it 
floats,  43. 

Iceland,  geysers  of,  14;  hot  .springs 
of,  14. 

India,  35.  36.  48:  animals  peculiar 
to,  109;  monsoons  of,  80:  plains 
of.  28;  plants  peculiar  to.  115; 
rainfall  of.  89,  93. 

Indian  Ocean,  41;  bed  of,  55:  cohir 
of,  53;  currents  of,  65;  form  of, 
54;  stoims  of,  81,  84:  tempera- 
ture of,  54;  tidal-wave  in,  .58. 

Indian  Race,  characteristics  of, lis. 

Industries  of  middle  latitudes.  121 ; 
of  the  United  States,  121, 124. 

Inland  seas,  49. 

Iran,  plateau  of.  36. 

Irrigation,  93,  120. 

Islands,  continental.  38;  coral,  how 
formed,  39.  40:  volc;inic.  38. 

Isothermal  lines,  74. 

Italian  Peninsula,  33. 

Japan,  65;  Current.  65 
Java,  volcanic  region.  20,  22. 
Jorullo,  formation  of,  15,  18. 
Jupiter,  planet,  7;  year  and  seasons 
of,  9,  10. 

KARAKOBirM  Mountains,  34;  gla 

ciers  of.  97. 
Keelfcss.  falls  of.  46. 
Khamsin  wind,  80. 
Khasia  Hills,  nunfall  on.  89. 
Khingan  Mountains.  35. 
Kilanea.  crater  of.  15. 
Kirghiz  Steppes,  36. 
Kong  Mountains.  37. 
Kuenlun  Mountains.  34. 


13° 


INDEX. 


Labor,  distribntion  of  dependent 
on  physical  geography,  131 ; 
l^'i-neml  law  concerning,  121. 

Labrador,  climate  of,  71;  plateau 
of,  31. 

Lake  Erie,  46;  Ontario,  46;  Elton, 
suit  from,  49 

LakcH,  distribution  of,  40  ;  fdrma- 
tioii  of,  48;  fresh  water,  48  ;  in 
Africa,  5() ;  in  Asia,  50  ;  in  Eu- 
rope, 49;  in  North  America,  49; 
in  South  America,  50;  ofticee  of, 
40;  salt.  48.  49. 

Land,  area  of,  26;  causes  of  depres- 
Hion  of,  29;  causes  of  elevation 
of,  38,  20;  distribution  of,  26; 
effects  of  elevations  of,  29;  ele- 
vation of,  27-37 ;  general  ar- 
rangement of  over  the  globe,  26; 
relation  of  to  air  and  water,  26. 

Land-breeze,  78. 

Lava,  emission  of  explained,  18; 
formation  of.  16;  streams  of,  18. 

Life  of  plants  and  animals,  101. 

Light,  diffusion  of,  how  caused,  99. 

lightning.  98. 

Line  of  no  variation,  history  of,  12. 

Lipari  Inlands.  18,  34. 

Lisl)on,  31,  22. 

Llama,  range  of,  113. 

Maelstrom,  60. 

Magnetic  needle,  12,  99;  poles,  13; 
storms,  12. 

Magnetism,  causes  of,  13;  of  the 
earth,  10;  uses  of,  13. 

Magnets,  origin  of,  10 ;  properties 
of,  10. 

Malay  Race.  117. 

Man,  conditions  favorable  to  ci\'i]i- 
zation  of,  118 ;  geogr.-iphical 
range  of,  116 ;  influence  of  on 
ph^'sical  geography,  118  ;  range 
of  plants  and  animals  extended 
by.  120. 

Mars,  planet.  7. 

Mediterranean  Sea,  47;  color  of.53; 
evaporation  from,  60;  tides  in,58- 

Mercury,  planet,  7  ;  year  and  sea- 
sons of,  9,  10. 

Mexico,  early  civilization  of,  118, 
rains  of,  92, 93 ;  table  lands  of,  28. 

Mines,  temperature  of,  13. 

Mirage,  99. 

Mississippi,  50;  bar  of,  47  ;  basin 
of,  51;  delta  of.  28,  47,  48;  sedi- 
ment carried  by,  47;  water  dis- 
charged by,  51. 

Mississippi  valley,  industries  of, 
124. 

Mist,  formation  of,  86. 

Moisture  of  the  air,  85. 

Mongolian  race,  characteristics  of, 
117. 

Monsoons,  cause  and  effects  of,  80. 

Mont  Blanc,  33,  70. 

Moun  Mountains,  36. 

Mountains,  formation  of,  1.5,  28; 
influence  of  on  climate,  29;  in- 
fluence of  on  drainage,  29;  regu- 
lators of  rainfall,  88. 

Mount  Everest,  34. 

Mozambique  Current,  65. 

Nebular  theorv,  7. 

Needle,  declination  and  dip  of,  12  ; 
variations  of,  12. 

Ne^':^o  Race,  117. 

Neptune,  planet,  7  ;  year  and  sea- 
sons of,  9,  10. 

Neutral  line,  10. 

Neve  of  snovvfields,  95. 

New  England  and  the  Gulf  States 
contrasted.  124. 

New  Zealand,  L'cysers  of,  14, 

Niag.iia  p-alls,  46. 

Nile,  48;  delta  of,  27,  47.  48;  over- 
flow of,  38,  52,  92;  rajiids  of.  46. 


North  Sea,  36. 

Norway,  29;  climate  of,  74. 

Nyassa  lake,  36. 

OcKAN  BASIN.**,  fomis  of,  54. 
Oceanic  circulation,  cauees  of,  65. 
Oceans,  54;  beds  i»f,  54,  55;  depth 

and  cxtt-nt  of,  54. 
Optical  phenomena,  99. 
Orkney  Ittlands,  17,  64. 

Pacific  Ocean,  36,  47;  bed  of,  55; 
coral  reefs  of,  41,  66;  currents 
of,  65;  depth  and  form  of,  54; 
influence  of  on  climate,  74  ; 
stonns  of,  84;  subsidence  of,  29, 
41;  tidal-wave  in,  57. 

Pacific  slope,  indusiries  of,  124. 

Pamir,  plateau  of,  ;i4. 

Pamperos,  winds  of  the  Andes,  80- 

Parime  Mountains,  32. 

Passes,  of  the  Alps,  29  ;  of  the 
Himalayas,  35. 

Pele'8  hair,  16. 

Peling  Mountains,  35. 

Pennsylvania,  22. 

Persia,  35;  plateau  of,  36. 

Peru,  22;  early  civUization  of.  118; 
rainless  region  of.  93;  table 
lands  of,  28 ;  winds  of,  80. 

Phosphore^cence,  53. 

Physical  geography,  defined,  125. 

Plains,  alluvial  and  marine,  27; 
centres  of  civilization,  28. 

Planets,  classification  of,  7;  effect 
of  inclination  of,  9;  inclination 
of  axes  of,  9,  10  ;  movements  of, 
8;  origin  of,  7;  seasons  of,  9,  10. 

Plants  and  animals,  geographical 
range  of,  102;  modifications  of 
by  climate,  102,  103;  mutual 
checks,  100 ;  mutual  depend- 
ence of,  101;  relations  between, 
101;  range  of  dependent  on  cli- 
mate, 102. 

Plants,  division  of  the  earth's  sur- 
face into  regions  of,  114;  food  of 
animals  supplied  by,  101;  mod- 
ification of  by  climate,  102;  oxy- 
gen prepared  by.  101;  range  of 
beverage,  107 ;  range  of  food, 
106  ;  range  of  medicinal,  107; 
range  of  spice  and  narcotic,  107; 
used  for  clothing,  107. 

Plateaus,  28-37;  connection  with 
civilization,  38;  elevation  of,  28; 
of  Asia,  36. 

Polar  currents,  benefits  of,  64,  65. 

Poles,  magnetic,  12. 

Polyp  coral,  description  of,  39 ; 
depth  at  which  he  works,  41. 

Pompeii,  17 

Precipitation,  cause  of,86;  effect  of 
on  sea- water,  66 

Pny  de  Dome,  69. 

Pyrenees  Mountains,  33. 

Quito,  atmospheric  pressure  at,  70. 

Race,  of  the  tide,  58. 

Races  of  men,  116. 

Radiation,  effect  of  on  climate,  71, 
74;  explained,  71. 

Rainbow,  99. 

Rain,  constant.  92:  formation  of. 
88:  periodical,  92;  variable,  93. 

Rainfall,  annual,  66 ;  distribution 
of,  8S:  general  cause  of,  88:  in 
India,  89;  in  Smith  America. 89; 
regions  of  deficiency  of,  93;  re- 
gions of  excess  of.  93;  regulators 
of.  88,  92.  "  j 

Rainless  regions,  93.^ 

Red  Sea.  36.  41;  evaporaiion  from,  i 
66;  temperature  of,  54;  tides  in,  I 
58.  i 

Regelation,  95. 

Rhone  river,  sediment  carried  , 
down  by,  47.  ! 


Rivers,  amount  of  ecdiment  trang- 
ported  by,  47 ;  bars  of,  47; 
branching  of  in  deltas,  48;  cat- 
aracts of,  46  ;  deposit  of  sedi- 
ment by,  47;  deltas  of,  47;  ero- 
sion by.  46  :  excavations  of 
gorges  by,  46;  floods  of,  51;  of- 
fi(ce  of.  46  ;  rapids  of,  46  ;  rela- 
tion of  to  ocean  life,  48;  sinu- 
osities of,  47  ;  sources  of,  46; 
eystem  of,  46;  tides  in,  (K);  water 
diJ^charged  by,  50;  waterfalls  of, 
46. 

Rocky  Mountains,  28,  '^),  51. 

Russia,  plains  of,  28. 

Sahara,  28;  aspect  of,  37;  eleva- 
tion of,  37;  influence  of  on  rain- 
fall, 80,  02  ;  temperature  of,  74  ; 
winds  of,  80- 

St.  Elmo's  Fire,  99. 

St.  Lawrence,  rapids  of,  46. 

St.  Michael,  hot  springs  of,  14. 

St.  Thomas,  storm  at,  83. 

Salt-lakes.  48,  49. 

Saltness  of  the  sea.  53;  effect  of 
on  the  circulation  of  the  sea,  66. 

Sandwich  Islands.  38. 

Saniorini  Island,  38. 

Sargasso  seas,  67. 

Saturn,  planet.  7. 

Scandinavian  Mountains,  fiords  of, 
34. 

Sea,  area  of,  52;  bottom  of,  54; 
color  of,  53:  circulation  of,  65; 
currents  of,  61,  64,  65;  fauna  of, 
114  ;  flora  of,  108  ;  influence  of 
on  climate,  71,  74;  movements 
of,  K,  .56,  57;  offices  of,  54; 
phosphorescence  of,  53:  sallness 
of,  53;  specific  gravity  of,  65; 
temperature  of,  53,  54,  66  ;  tides 
in,  56,  57,  58;  waves  of,  55. 

Sea-breeze,  78. 

Sea-level.  74. 

Seasons,  causes  of,  9;  rainy  and 
dry,  93. 

Selvas,  27. 

Siberia,  35 ;  mastodons  found  in, 
102;  plain  of.  36. 

Sierra  Nevada  Mountains,  89. 

Simoom,  effects  of,  80. 

Sirocco,  described.  80. 

Skaptar  JOkul,  18. 

Snow,  formation  of.  94;  offices  of, 
94;  quautiiy  of,  94:  where  most 
abundant.  94. 

Snow-line,  height  of,  94. 

Snow  Mountains,  .%. 

Solar  system,  7. 

Solomon  Isles,  16. 

Specific  gra\'ity.  a  cause  of  oceanic 
circulation,  65  ;  changes  in,  how 
effected,  66. 

Springs,  dependent  upon  rainfall, 
45;  depth  of,  45;  hot.  45;  inter- 
mittent. 45  ;  mineral,  4^;  origin 
of,  45;  substances  dissolved  in, 
45:  surface,  45;  temperature  of, 
14. 

Steppes,  27  ;  Kirghiz,  36. 

Storms,  67,  84.  85:  areas  of.  84: 
cause  of,  81;  distribnti<m  of.  81; 
irregularity  of  on  land.  83;  laws 
of.  82.  &3;  magnetic,  12;  of  Uni- 
ted Stales,  8);  prediction  of,  S5 

Stromboli,  the  light  of,  16. 

Subsidence,  of  the  land,  29;  of  the 
sea,  41. 

Sun,  a  cause  of  atmospheric  circu- 
lation, 76:   composition  of,  7: 
heat  derived  from,  7;   position 
in  the  solar-system.  6;  size  of,  6. 
Sun-spots  and  magnetism,  12. 

Tablelands,  28. 

Tahiti,  40;  formation  of,  41 

Temperature,  zones  of,  75. 


Texas,  winds  of,  92. 

Thian  Shan  Mountains,  34,  3*i 

Thibet,  elevation  of,  34;  plateau 
of.  28,  35,  36,  70. 

Thunder,  cause  of,  98;  i-torms,  98. 

Tidal-wave,  in  the  oceans,  58;  in 
rivers,  60;  movement  of,  57,  58; 
origin  of,  57. 

Tides,  aspect  of,  56 :  cans-e  of.  56. 
57;  differences  of  on  same  coaf^t, 
60;  height  of,  5S;  high  and  low, 
57;  in  rivers,  60 ;  spring  and 
neap,  57;  why  t-o  called,  57. 

Titicaca,  plateau  of,  28. 

Tornadoes,  8L 

Torricelli,  experiment  of,  69. 

Trade-winds,  76. 

Tsien-tsang,  bore  of  the,  60. 

United  States,  industries  of,  121, 

124,  125. 
Ural  Mountains.  34  ;  river,  49. 
Useful  trees,  range  of,  108. 

Valleys,  formation  of,  29:  deep- 
ened by  running  water,  29;  lon- 
gitudinal and  tiai.sverbe,29. 

Vapor  of  water,  69;  amount  of  in 
the  air,  85;  tffect  of  on  circula- 
tion of  the  air.  76;  offices  of,  69. 

Vegetation,  horizontal  zones  of, 
103:  of  the  sea,  108;  regulated 
by  climate.  103 ;  regulated  by 
height  above  the  sea-level,  106; 
vertical  zones  of,  106. 

Venus,  planet.  7:  seasons  of,  10. 

Vesuvius,  eruption  of,  16. 17,  22,34, 

Volcanic,  belts,  18,  38:  islands,  for- 
mation of,  38. 

Volcanoes,  causes  of,  20;  distribu- 
tion of,  18;  dormant  and  ex- 
tinct,16:  eruptions  of  described, 
17,  18;  formation  and  height  of, 
15;  materials  ejected  from,  16; 
proof  of  the  earth's  internal 
heat,  14  ;  quantity  of  matter 
ejected.  16:  where  most  active, 
20. 

Water,  action  of  on  the  earth's 
surface.  29 ;  boiling-point  of, 
how  affected,  70;  capacity  of  for 
heat. 44;  circulation  of.  44;  C(»m- 
position  of,  43;  condensation  of, 
44:  evaporation  of,  44:  expan- 
sion of,  43;  expansive  force  of 
when  freezing,  43;  forms  of,  43; 
solvent  power  of,  44. 

Waterfalls,  46. 

Waterspouts,  84. 

Waves,  cause  of,  55;  crest  and 
breadth  of.  55;  earthquake.  21; 
force  and  work  of.  55 ;  height 
of,  56;  limited  extent  of  influ- 
ence of,  56;  velocity  of,  55. 

Weather  forecasts,  84. 

Wells,  13. 

West  Indies,  38.  41;  storms  of.  81. 

Whale,  range  of,  114. 

Whiripool,  60. 

Whiriwinds,  84;  dust,  84. 

Winds,  causes  of.  75,  76;  constant, 
76;  counter-trades,  origin  of,  77; 
dry.  92;  effect  of  on  evapora- 
tion. ?(i:  effect  of  on  ocean  cur- 
rents, 67;  influence  of  on  cli- 
mate. 74;  influence  of  on  rain- 
fall. 92;  mountain,  80;  office  of, 
80.  101:  periodical,  78.80:  polar, 
78;  trade,  76;  variable,  77;  wet, 
89,  92. 

Yakttsk,  temperature  of,  74. 
Yellowstone  Park,  geysers  of,  14. 

Zoological  regions  defined.  109. 
Zones,  of  vegetation.  103;  of  animal 
life.  108;  of  temperature,  75. 


university  of  CaUfomia  ^ 

SOUTHERN  REGIONAL  UBRARY^FACILIT^^^^ 

3°^  °^r.TZc^lU  cTuFORNlA  90095-1388 

UOS  ANGELtb,  v-«>-  borrowed. 

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